Since assignments on M2M or reverse FK descriptors is composed of a `clear()`,
followed by an `add()`, `clear()` could potentially affect the value of the
assigned queryset before the `add()` step; pre-evaluating it solves the problem.
This patch fixes the issue for ForeignRelatedObjectsDescriptor,
ManyRelatedObjectsDescriptor, and ReverseGenericRelatedObjectsDescriptor.
It completes 6cb6e1 which addressed ReverseManyRelatedObjectsDescriptor.
The original patch for custom prefetches didn't allow usage of custom
queryset for single valued relations (along ForeignKey or OneToOneKey).
Allowing these enables calling performance oriented queryset methods like
select_related or defer/only.
Thanks @akaariai and @timgraham for the reviews. Refs #17001.
ForeignKey or ManyToManyField attribute ``limit_choices_to`` can now
be a callable that returns either a ``Q`` object or a dict.
Thanks michael at actrix.gen.nz for the original suggestion.
This is the result of Christopher Medrela's 2013 Summer of Code project.
Thanks also to Preston Holmes, Tim Graham, Anssi Kääriäinen, Florian
Apolloner, and Alex Gaynor for review notes along the way.
Also: Fixes#8579, fixes#3055, fixes#19844.
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 fa7a7195f1
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 18 10:53:24 2014 +0200
Added lookup registration API docs
commit eb1c8ce164
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Tue Jan 14 18:59:36 2014 +0200
Release notes and other minor docs changes
commit 11501c29c9
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 83173b960e
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Jan 12 19:59:12 2014 +0200
Renamed Extract -> Transform
commit 3b18d9f3a1
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Jan 12 19:51:53 2014 +0200
Removed suggestion of temporary lookup registration from docs
commit 21d0c7631c
Merge: 2509006f2dc442
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 f2dc4429a1
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 2509006506
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Jan 12 13:19:13 2014 +0200
Removed unused import
commit 4fba5dfaa0
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 22:34:41 2014 +0200
Added docs to index
commit 6d53963f37
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 22:10:24 2014 +0200
Dead code removal
commit f9cc039007
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 19:00:43 2014 +0200
A new try for docs
commit 33aa18a6e3
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 14:57:12 2014 +0200
Renamed get_cols to get_group_by_cols
commit c7d5f8661b
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 90e7004ec1
Merge: 66649fff7c2c0a
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 13:21:01 2014 +0200
Merge branch 'master' into lookups_3
commit 66649ff891
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Jan 11 13:16:01 2014 +0200
Some rewording in docs
commit 31b8faa627
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 29 15:52:29 2013 +0200
Cleanup based on review comments
commit 1016159f34
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 193cd097ca
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Dec 28 17:57:58 2013 +0200
Fixed#11722 -- iexact=F() produced invalid SQL
commit 08ed3c3b49
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 b99c8d83c9
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Dec 21 23:06:29 2013 +0200
Fixed review notes by Loic
commit 049eebc070
Merge: ed8fab7b80a835
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 ed8fab7fe8
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Dec 21 22:47:23 2013 +0200
Made Extracts aware of full lookup path
commit 27a57b7aed
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 1 21:10:11 2013 +0200
Removed debugger import
commit 074e0f5aca
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 1 21:02:16 2013 +0200
GIS lookup support added
commit 760e28e72b
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 1 20:04:31 2013 +0200
Removed usage of Constraint, used Lookup instead
commit eac4776684
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 1 02:22:30 2013 +0200
Minor cleanup of Lookup API
commit 2adf50428d
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sun Dec 1 02:14:19 2013 +0200
Added documentation, polished implementation
commit 32c04357a8
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Sat Nov 30 23:10:15 2013 +0200
Avoid OrderedDict creation on lookup aggregate check
commit 7c8b3a32cc
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 4d219d4cde
Author: Anssi Kääriäinen <akaariai@gmail.com>
Date: Wed Nov 27 22:07:30 2013 +0200
Initial implementation of custom lookups
Returning None on errors required unpythonic error checking and was
inconsistent with get_app_config.
get_model was a private API until the previous commit, but given that it
was certainly used in third party software, the change is explained in
the release notes.
Applied the same change to get_registered_model, which is a new private
API introduced during the recent refactoring.
Got rid of AppConfig._stub. As a side effect, app_cache.app_configs now
only contains entries for applications that are in INSTALLED_APPS, which
is a good thing and will allow dramatic simplifications (which I will
perform in the next commit). That required adjusting all methods that
iterate on app_configs without checking the "installed" flag, hence the
large changes in get_model[s].
Introduced AppCache.all_models to store models:
- while the app cache is being populated and a suitable app config
object to register models isn't available yet;
- for applications that aren't in INSTALLED_APPS since they don't have
an app config any longer.
Replaced get_model(seed_cache=False) by registered_model() which can be
kept simple and safe to call at any time, and removed the seed_cache
argument to get_model[s]. There's no replacement for that private API.
Allowed non-master app caches to go through populate() as it is now
safe to do so. They were introduced in 1.7 so backwards compatibility
isn't a concern as long as the migrations framework keeps working.
The `remove()` and `clear()` methods of the related managers created by
`ForeignKey`, `GenericForeignKey`, and `ManyToManyField` suffered from a
number of issues. Some operations ran multiple data modifying queries without
wrapping them in a transaction, and some operations didn't respect default
filtering when it was present (i.e. when the default manager on the related
model implemented a custom `get_queryset()`).
Fixing the issues introduced some backward incompatible changes:
- The implementation of `remove()` for `ForeignKey` related managers changed
from a series of `Model.save()` calls to a single `QuerySet.update()` call.
The change means that `pre_save` and `post_save` signals aren't called anymore.
- The `remove()` and `clear()` methods for `GenericForeignKey` related
managers now perform bulk delete so `Model.delete()` isn't called anymore.
- The `remove()` and `clear()` methods for `ManyToManyField` related
managers perform nested queries when filtering is involved, which may
or may not be an issue depending on the database and the data itself.
Refs. #3871, #21174.
Thanks Anssi Kääriäinen and Tim Graham for the reviews.
This patch introduces the Prefetch object which allows customizing prefetch
operations.
This enables things like filtering prefetched relations, calling select_related
from a prefetched relation, or prefetching the same relation multiple times
with different querysets.
When a Prefetch instance specifies a to_attr argument, the result is stored
in a list rather than a QuerySet. This has the fortunate consequence of being
significantly faster. The preformance improvement is due to the fact that we
save the costly creation of a QuerySet instance.
Thanks @akaariai for the original patch and @bmispelon and @timgraham
for the reviews.
Previously, if a database request spanned a related object manager, the
first manager encountered would cause a request to the router, and this
would bind all subsequent queries to the same database returned by the
router. Unfortunately, the first router query would be performed using
a read request to the router, resulting in bad routing information being
used if the subsequent query was actually a write.
This change defers the call to the router until the final query is acutally
made.
It includes a small *BACKWARDS INCOMPATIBILITY* on an edge case - see the
release notes for details.
Thanks to Paul Collins (@paulcollinsiii) for the excellent debugging
work and patch.
valtron
Loic Bistuer
Aymeric Augustin
Tim Graham
Akis Kesoglou
Andrew Godwin
Claude Paroz
Akis Kesoglou
Loic Bistuer
Russell Keith-Magee
Christopher Medrela
Albert Wang
Christopher Adams
Robert Stapenhurst
Alex Gaynor
Anssi Kääriäinen
Jonas Gastal
Simon Charette
Baptiste Mispelon
Alasdair Nicol