django/docs/howto/custom-lookups.txt

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Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
==============
Custom Lookups
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
==============
.. versionadded:: 1.7
.. currentmodule:: django.db.models
Django offers a wide variety of :ref:`built-in lookups <field-lookups>` for
filtering (for example, ``exact`` and ``icontains``). This documentation
explains how to write custom lookups and how to alter the working of existing
lookups. For the API references of lookups, see the :doc:`/ref/models/lookups`.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
A simple lookup example
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
~~~~~~~~~~~~~~~~~~~~~~~
Let's start with a simple custom lookup. We will write a custom lookup ``ne``
which works opposite to ``exact``. ``Author.objects.filter(name__ne='Jack')``
will translate to the SQL::
"author"."name" <> 'Jack'
This SQL is backend independent, so we don't need to worry about different
databases.
There are two steps to making this work. Firstly we need to implement the
lookup, then we need to tell Django about it. The implementation is quite
straightforward::
from django.db.models import Lookup
class NotEqual(Lookup):
lookup_name = 'ne'
def as_sql(self, qn, connection):
lhs, lhs_params = self.process_lhs(qn, connection)
rhs, rhs_params = self.process_rhs(qn, connection)
params = lhs_params + rhs_params
return '%s <> %s' % (lhs, rhs), params
To register the ``NotEqual`` lookup we will just need to call
``register_lookup`` on the field class we want the lookup to be available. In
this case, the lookup makes sense on all ``Field`` subclasses, so we register
it with ``Field`` directly::
from django.db.models.fields import Field
Field.register_lookup(NotEqual)
Lookup registration can also be done using a decorator pattern::
from django.db.models.fields import Field
@Field.registerLookup
class NotEqualLookup(Lookup):
# ...
.. versionchanged:: 1.8
The ability to use the decorator pattern was added.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
We can now use ``foo__ne`` for any field ``foo``. You will need to ensure that
this registration happens before you try to create any querysets using it. You
could place the implementation in a ``models.py`` file, or register the lookup
in the ``ready()`` method of an ``AppConfig``.
Taking a closer look at the implementation, the first required attribute is
``lookup_name``. This allows the ORM to understand how to interpret ``name__ne``
and use ``NotEqual`` to generate the SQL. By convention, these names are always
lowercase strings containing only letters, but the only hard requirement is
that it must not contain the string ``__``.
We then need to define the ``as_sql`` method. This takes a ``SQLCompiler``
object, called ``qn``, and the active database connection. ``SQLCompiler``
objects are not documented, but the only thing we need to know about them is
that they have a ``compile()`` method which returns a tuple containing a SQL
string, and the parameters to be interpolated into that string. In most cases,
you don't need to use it directly and can pass it on to ``process_lhs()`` and
``process_rhs()``.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
A ``Lookup`` works against two values, ``lhs`` and ``rhs``, standing for
left-hand side and right-hand side. The left-hand side is usually a field
reference, but it can be anything implementing the :ref:`query expression API
<query-expression>`. The right-hand is the value given by the user. In the
example ``Author.objects.filter(name__ne='Jack')``, the left-hand side is a
reference to the ``name`` field of the ``Author`` model, and ``'Jack'`` is the
right-hand side.
We call ``process_lhs`` and ``process_rhs`` to convert them into the values we
need for SQL using the ``qn`` object described before. These methods return
tuples containing some SQL and the parameters to be interpolated into that SQL,
just as we need to return from our ``as_sql`` method. In the above example,
``process_lhs`` returns ``('"author"."name"', [])`` and ``process_rhs`` returns
``('"%s"', ['Jack'])``. In this example there were no parameters for the left
hand side, but this would depend on the object we have, so we still need to
include them in the parameters we return.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
Finally we combine the parts into a SQL expression with ``<>``, and supply all
the parameters for the query. We then return a tuple containing the generated
SQL string and the parameters.
A simple transformer example
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The custom lookup above is great, but in some cases you may want to be able to
chain lookups together. For example, let's suppose we are building an
application where we want to make use of the ``abs()`` operator.
We have an ``Experiment`` model which records a start value, end value, and the
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
change (start - end). We would like to find all experiments where the change
was equal to a certain amount (``Experiment.objects.filter(change__abs=27)``),
2014-01-19 04:31:35 +08:00
or where it did not exceed a certain amount
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
(``Experiment.objects.filter(change__abs__lt=27)``).
.. note::
This example is somewhat contrived, but it nicely demonstrates the range of
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
functionality which is possible in a database backend independent manner,
and without duplicating functionality already in Django.
We will start by writing a ``AbsoluteValue`` transformer. This will use the SQL
function ``ABS()`` to transform the value before comparison::
from django.db.models import Transform
class AbsoluteValue(Transform):
lookup_name = 'abs'
def as_sql(self, qn, connection):
lhs, params = qn.compile(self.lhs)
return "ABS(%s)" % lhs, params
Next, let's register it for ``IntegerField``::
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
from django.db.models import IntegerField
IntegerField.register_lookup(AbsoluteValue)
2014-01-19 04:31:35 +08:00
We can now run the queries we had before.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
``Experiment.objects.filter(change__abs=27)`` will generate the following SQL::
SELECT ... WHERE ABS("experiments"."change") = 27
By using ``Transform`` instead of ``Lookup`` it means we are able to chain
further lookups afterwards. So
``Experiment.objects.filter(change__abs__lt=27)`` will generate the following
SQL::
SELECT ... WHERE ABS("experiments"."change") < 27
Note that in case there is no other lookup specified, Django interprets
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
``change__abs=27`` as ``change__abs__exact=27``.
When looking for which lookups are allowable after the ``Transform`` has been
applied, Django uses the ``output_field`` attribute. We didn't need to specify
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
this here as it didn't change, but supposing we were applying ``AbsoluteValue``
to some field which represents a more complex type (for example a point
relative to an origin, or a complex number) then we may have wanted to specify
that the transform returns a ``FloatField`` type for further lookups. This can
be done by adding an ``output_field`` attribute to the transform::
from django.db.models import FloatField, Transform
class AbsoluteValue(Transform):
lookup_name = 'abs'
def as_sql(self, qn, connection):
lhs, params = qn.compile(self.lhs)
return "ABS(%s)" % lhs, params
@property
def output_field(self):
return FloatField()
This ensures that further lookups like ``abs__lte`` behave as they would for
a ``FloatField``.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
Writing an efficient abs__lt lookup
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When using the above written ``abs`` lookup, the SQL produced will not use
indexes efficiently in some cases. In particular, when we use
``change__abs__lt=27``, this is equivalent to ``change__gt=-27`` AND
``change__lt=27``. (For the ``lte`` case we could use the SQL ``BETWEEN``).
So we would like ``Experiment.objects.filter(change__abs__lt=27)`` to generate
the following SQL::
SELECT .. WHERE "experiments"."change" < 27 AND "experiments"."change" > -27
The implementation is::
from django.db.models import Lookup
class AbsoluteValueLessThan(Lookup):
lookup_name = 'lt'
def as_sql(self, qn, connection):
lhs, lhs_params = qn.compile(self.lhs.lhs)
rhs, rhs_params = self.process_rhs(qn, connection)
params = lhs_params + rhs_params + lhs_params + rhs_params
return '%s < %s AND %s > -%s' % (lhs, rhs, lhs, rhs), params
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
AbsoluteValue.register_lookup(AbsoluteValueLessThan)
There are a couple of notable things going on. First, ``AbsoluteValueLessThan``
isn't calling ``process_lhs()``. Instead it skips the transformation of the
``lhs`` done by ``AbsoluteValue`` and uses the original ``lhs``. That is, we
want to get ``27`` not ``ABS(27)``. Referring directly to ``self.lhs.lhs`` is
safe as ``AbsoluteValueLessThan`` can be accessed only from the
``AbsoluteValue`` lookup, that is the ``lhs`` is always an instance of
``AbsoluteValue``.
Notice also that as both sides are used multiple times in the query the params
need to contain ``lhs_params`` and ``rhs_params`` multiple times.
The final query does the inversion (``27`` to ``-27``) directly in the
database. The reason for doing this is that if the ``self.rhs`` is something else
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
than a plain integer value (for example an ``F()`` reference) we can't do the
transformations in Python.
.. note::
In fact, most lookups with ``__abs`` could be implemented as range queries
2014-01-19 04:31:35 +08:00
like this, and on most database backends it is likely to be more sensible to
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
do so as you can make use of the indexes. However with PostgreSQL you may
want to add an index on ``abs(change)`` which would allow these queries to
be very efficient.
A bilateral transformer example
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``AbsoluteValue`` example we discussed previously is a transformation which
applies to the left-hand side of the lookup. There may be some cases where you
want the transformation to be applied to both the left-hand side and the
right-hand side. For instance, if you want to filter a queryset based on the
equality of the left and right-hand side insensitively to some SQL function.
Let's examine the simple example of case-insensitive transformation here. This
transformation isn't very useful in practice as Django already comes with a bunch
of built-in case-insensitive lookups, but it will be a nice demonstration of
bilateral transformations in a database-agnostic way.
We define an ``UpperCase`` transformer which uses the SQL function ``UPPER()`` to
transform the values before comparison. We define
:attr:`bilateral = True <django.db.models.Transform.bilateral>` to indicate that
this transformation should apply to both ``lhs`` and ``rhs``::
from django.db.models import Transform
class UpperCase(Transform):
lookup_name = 'upper'
bilateral = True
def as_sql(self, qn, connection):
lhs, params = qn.compile(self.lhs)
return "UPPER(%s)" % lhs, params
Next, let's register it::
from django.db.models import CharField, TextField
CharField.register_lookup(UpperCase)
TextField.register_lookup(UpperCase)
Now, the queryset ``Author.objects.filter(name__upper="doe")`` will generate a case
insensitive query like this::
SELECT ... WHERE UPPER("author"."name") = UPPER('doe')
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Writing alternative implementations for existing lookups
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
Sometimes different database vendors require different SQL for the same
operation. For this example we will rewrite a custom implementation for
MySQL for the NotEqual operator. Instead of ``<>`` we will be using ``!=``
operator. (Note that in reality almost all databases support both, including
all the official databases supported by Django).
2014-03-01 00:44:03 +08:00
We can change the behavior on a specific backend by creating a subclass of
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
``NotEqual`` with a ``as_mysql`` method::
class MySQLNotEqual(NotEqual):
def as_mysql(self, qn, connection):
lhs, lhs_params = self.process_lhs(qn, connection)
rhs, rhs_params = self.process_rhs(qn, connection)
params = lhs_params + rhs_params
return '%s != %s' % (lhs, rhs), params
Field.register_lookup(MySQLNotExact)
We can then register it with ``Field``. It takes the place of the original
2014-01-19 04:31:35 +08:00
``NotEqual`` class as it has the same ``lookup_name``.
Fixed #16187 -- refactored ORM lookup system Allowed users to specify which lookups or transforms ("nested lookus") are available for fields. The implementation is now class based. Squashed commit of the following: commit fa7a7195f1952a9c8dea7f6e89ee13f81757eda7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 18 10:53:24 2014 +0200 Added lookup registration API docs commit eb1c8ce164325e0d8641f14202e12486c70efdb6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Tue Jan 14 18:59:36 2014 +0200 Release notes and other minor docs changes commit 11501c29c9352d17f22f3a0f59d3b805913dedcc Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 20:53:03 2014 +0200 Forgot to add custom_lookups tests in prev commit commit 83173b960ea7eb2b24d573f326be59948df33536 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:59:12 2014 +0200 Renamed Extract -> Transform commit 3b18d9f3a1bcdd93280f79654eba0efa209377bd Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 19:51:53 2014 +0200 Removed suggestion of temporary lookup registration from docs commit 21d0c7631c161fc0c67911480be5d3f13f1afa68 Merge: 2509006 f2dc442 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 09:38:23 2014 -0800 Merge pull request #2 from mjtamlyn/lookups_3 Reworked custom lookups docs. commit f2dc4429a1da04c858364972eea57a35a868dab4 Author: Marc Tamlyn <marc.tamlyn@gmail.com> Date: Sun Jan 12 13:15:05 2014 +0000 Reworked custom lookups docs. Mostly just formatting and rewording, but also replaced the example using ``YearExtract`` to use an example which is unlikely to ever be possible directly in the ORM. commit 250900650628d1f11beadb22814abd666029fb81 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Jan 12 13:19:13 2014 +0200 Removed unused import commit 4fba5dfaa022653ffa72497258ffd8f8b7476f92 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:34:41 2014 +0200 Added docs to index commit 6d53963f375c77a1f287833b19b976d23f36c30b Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 22:10:24 2014 +0200 Dead code removal commit f9cc0390078e21f1ea5a7bc1f15b09f8f6b0904d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 19:00:43 2014 +0200 A new try for docs commit 33aa18a6e3c831930bda0028222a26f9c1d96e66 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:57:12 2014 +0200 Renamed get_cols to get_group_by_cols commit c7d5f8661b7d364962bed2e6f81161c1b4f1bcc3 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 14:45:53 2014 +0200 Altered query string customization for backends vendors The new way is trying to call first method 'as_' + connection.vendor. If that doesn't exist, then call as_sql(). Also altered how lookup registration is done. There is now RegisterLookupMixin class that is used by Field, Extract and sql.Aggregate. This allows one to register lookups for extracts and aggregates in the same way lookup registration is done for fields. commit 90e7004ec14e15503f828cc9bde2a7dab593814d Merge: 66649ff f7c2c0a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:21:01 2014 +0200 Merge branch 'master' into lookups_3 commit 66649ff891c7c73c7eecf6038c9a6802611b5d8a Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Jan 11 13:16:01 2014 +0200 Some rewording in docs commit 31b8faa62714b4b6b6057a9f5cc106c4dd73caab Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 29 15:52:29 2013 +0200 Cleanup based on review comments commit 1016159f34674c0df871ed891cde72be8340bb5d Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 18:37:04 2013 +0200 Proof-of-concept fix for #16731 Implemented only for SQLite and PostgreSQL, and only for startswith and istartswith lookups. commit 193cd097ca8f2cc6a911e57b8e3fb726f96ee6a6 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 28 17:57:58 2013 +0200 Fixed #11722 -- iexact=F() produced invalid SQL commit 08ed3c3b49e100ed9019831e770c25c8f61b70f9 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:59:52 2013 +0200 Made Lookup and Extract available from django.db.models commit b99c8d83c972786c6fcd0e84c9e5cb08c1368300 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 23:06:29 2013 +0200 Fixed review notes by Loic commit 049eebc0703c151127f4f0265beceea7b8b39e72 Merge: ed8fab7 b80a835 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:53:10 2013 +0200 Merge branch 'master' into lookups_3 Conflicts: django/db/models/fields/__init__.py django/db/models/sql/compiler.py django/db/models/sql/query.py tests/null_queries/tests.py commit ed8fab7fe8867ff3eb801c3697a426478387bb2f Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Dec 21 22:47:23 2013 +0200 Made Extracts aware of full lookup path commit 27a57b7aed91b2f346abc4a77da838bffa17c727 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:10:11 2013 +0200 Removed debugger import commit 074e0f5aca0572e368c11e6d2c73c9026e7d63d7 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 21:02:16 2013 +0200 GIS lookup support added commit 760e28e72bae475b442b026650969b0d182dbe53 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 20:04:31 2013 +0200 Removed usage of Constraint, used Lookup instead commit eac47766844b90e7d3269e7a8c012eee34ec0093 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:22:30 2013 +0200 Minor cleanup of Lookup API commit 2adf50428d59a783078b0da3d5d035106640c899 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sun Dec 1 02:14:19 2013 +0200 Added documentation, polished implementation commit 32c04357a87e3727a34f8c5e6ec0114d1fbbb303 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:10:15 2013 +0200 Avoid OrderedDict creation on lookup aggregate check commit 7c8b3a32cc17b4dbca160921d48125f1631e0df4 Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Sat Nov 30 23:04:34 2013 +0200 Implemented nested lookups But there is no support of using lookups outside filtering yet. commit 4d219d4cdef21d9c14e5d6b9299d583d1975fcba Author: Anssi Kääriäinen <akaariai@gmail.com> Date: Wed Nov 27 22:07:30 2013 +0200 Initial implementation of custom lookups
2014-01-18 17:09:43 +08:00
When compiling a query, Django first looks for ``as_%s % connection.vendor``
methods, and then falls back to ``as_sql``. The vendor names for the in-built
backends are ``sqlite``, ``postgresql``, ``oracle`` and ``mysql``.
How Django determines the lookups and transforms which are used
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In some cases you may wish to dynamically change which ``Transform`` or
``Lookup`` is returned based on the name passed in, rather than fixing it. As
an example, you could have a field which stores coordinates or an arbitrary
dimension, and wish to allow a syntax like ``.filter(coords__x7=4)`` to return
the objects where the 7th coordinate has value 4. In order to do this, you
would override ``get_lookup`` with something like::
class CoordinatesField(Field):
def get_lookup(self, lookup_name):
if lookup_name.startswith('x'):
try:
dimension = int(lookup_name[1:])
except ValueError:
pass
finally:
return get_coordinate_lookup(dimension)
return super(CoordinatesField, self).get_lookup(lookup_name)
You would then define ``get_coordinate_lookup`` appropriately to return a
``Lookup`` subclass which handles the relevant value of ``dimension``.
There is a similarly named method called ``get_transform()``. ``get_lookup()``
should always return a ``Lookup`` subclass, and ``get_transform()`` a
``Transform`` subclass. It is important to remember that ``Transform``
objects can be further filtered on, and ``Lookup`` objects cannot.
When filtering, if there is only one lookup name remaining to be resolved, we
will look for a ``Lookup``. If there are multiple names, it will look for a
``Transform``. In the situation where there is only one name and a ``Lookup``
is not found, we look for a ``Transform`` and then the ``exact`` lookup on that
``Transform``. All call sequences always end with a ``Lookup``. To clarify:
- ``.filter(myfield__mylookup)`` will call ``myfield.get_lookup('mylookup')``.
- ``.filter(myfield__mytransform__mylookup)`` will call
``myfield.get_transform('mytransform')``, and then
``mytransform.get_lookup('mylookup')``.
- ``.filter(myfield__mytransform)`` will first call
``myfield.get_lookup('mytransform')``, which will fail, so it will fall back
to calling ``myfield.get_transform('mytransform')`` and then
``mytransform.get_lookup('exact')``.