This requires GEOS >= 3.3.0 to function properly. On previous
versions, the Z dimension will simply not appear in the wkt.
Disabled OpenLayers editing for 3D geometries (unsupported).
Thanks goes to void for the comprehensive report, to Pedro Mourelle for
the fix and to Bryan Veloso, Łukasz Rekucki and Claude Paroz for the
review.
This fix includes the following changes:
* Modified layout to top-aligned labels.
* Added 'air' for inputs (the padding was really needed there.). It
adjust good to zoom in/out.
* Removed float attributes from label and inputs in login form.
* Removed useless text-align property.
* Grouped related methods together -- with banner comments :/
* Described which methods are intended to be implemented in backends.
* Added docstrings.
* Used the same order in all wrappers.
Squashed commit of the following:
commit 2181d833ed1a2e422494738dcef311164c4e097e
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Wed Feb 27 14:28:39 2013 +0100
Fixed#15901 -- Wrapped all PEP-249 exceptions.
commit 5476a5d93c19aa2f928c497d39ce6e33f52694e2
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Feb 26 17:26:52 2013 +0100
Added PEP 3134 exception chaining.
Thanks Jacob Kaplan-Moss for the suggestion.
commit 9365fad0a650328002fb424457d675a273c95802
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Feb 26 17:13:49 2013 +0100
Improved API for wrapping database errors.
Thanks Alex Gaynor for the proposal.
commit 1b463b765f2826f73a8d9266795cd5da4f8d5e9e
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Feb 26 15:00:39 2013 +0100
Removed redundant exception wrapping.
This is now taken care of by the cursor wrapper.
commit 524bc7345a724bf526bdd2dd1bcf5ede67d6bb5c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Feb 26 14:55:10 2013 +0100
Wrapped database exceptions in the base backend.
This covers the most common PEP-249 APIs:
- Connection APIs: close(), commit(), rollback(), cursor()
- Cursor APIs: callproc(), close(), execute(), executemany(),
fetchone(), fetchmany(), fetchall(), nextset().
Fixed#19920.
commit a66746bb5f0839f35543222787fce3b6a0d0a3ea
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Feb 26 14:53:34 2013 +0100
Added a wrap_database_exception context manager and decorator.
It re-throws backend-specific exceptions using Django's common wrappers.
There were a couple of errors in ._dirty flag handling:
* It started as None, but was never reset to None.
* The _dirty flag was sometimes used to indicate if the connection
was inside transaction management, but this was not done
consistently. This also meant the flag had three separate values.
* The None value had a special meaning, causing for example inability
to commit() on new connection unless enter/leave tx management was
done.
* The _dirty was tracking "connection in transaction" state, but only
in managed transactions.
* Some tests never reset the transaction state of the used connection.
* And some additional less important changes.
This commit has some potential for regressions, but as the above list
shows, the current situation isn't perfect either.
Fixes#19584.
This implies stop storing file path command line arguments in envvars as
a security measure to start relying on with Popen's shell=False instead,
and addition of an 'utils' module.
Thanks kmichel_wgs for the report.
This function is now the de facto standard function for rendering values in a
template, and is imported by two other built-in template modules. It shouldn't
have a leading underscore.
The content of ifchanged template tag was rendered twice: first time, to
compare it with the previous value and the second time, to return the
rendered output.
Previously, the ifchanged node stored state on `self._last_seen`,
thereby giving undesired results when the node is reused by another
thread at the same time (e.g. globally caching a Template object).
Thanks to akaihola for the report and Diederik van der Boor and
Bas Peschier for the patch.
Changed the ip_address field for Comment to GenericIPAddressField. Added
instructions to the release notes on how to update the schema of existing
databases.
Change patch from https://code.djangoproject.com/ticket/5568
to work on modern Django.
Add special case for MySQL which has different syntax for DROP INDEX.
Add unit tests for the new functionality.
When iteration over a queryset raised an exception, the result cache
remained initialized with an empty list, so subsequent iterations returned
an empty list instead of raising an exception
The regression was likely caused by the fix in #19606 which adjusted
Oracle's unicode detection, though it seems this would have been an
issue in some configurations even before.
Querying the reverse side of nullable to_field relation, where both
sides can contain null values resulted in incorrect results. The reason
was not detecting '' as NULL.
Refs #17541
There was a regression in case two models inherited the same parent,
and one contained a foreign key to other. When select_related travelled
the foreign key the other model reused the parent join made by the
first model. This was likely caused by Query.join_parent_model()
addition in commit 68985db482.
Thanks to Trac alias loic84 for report & tests.
The admin_widgets tests were issuing click() to the browser but
didn't wait for the effects of those clicks. This caused the resulting
request to be processed concurrently with the test case. When using
in-memory SQLite this caused weird failures.
Also added wait_page_loaded() to admin selenium tests for code
reuse.
Fixed#19856
The join promote=True was over-aggressive in select_related handling.
After that was removed, the only other user was query.combine(). That
use case is very easy to handle locally, so there is no more need for
the join(promote=True) flag.
Refs #19849.
This controls whether or not a database level cosntraint is created. This is useful in a few specialized circumstances, but in general should not be used!
The refactoring mainly concentrates on making sure the inner and outer
query agree about the split position. The split position is where the
multijoin happens, and thus the split position also determines the
columns used in the "WHERE col1 IN (SELECT col2 from ...)" condition.
This commit fixes a regression caused by #10790 and commit
69597e5bcc. The regression was caused
by wrong cols in the split position.
Django used to check the version of MySQL before handling the first
request, which required:
- opening a connection
- closing it, to avoid holding it idle until the first request.
This code isn't necessary any longer since Django dropped support for
some versions of MySQL, and other database backends don't implement a
similar dance. For consistency and maintenability, remove it.
Reverts 4423757c0c.
Closes#18135.
Thanks Carl Meyer for the review.
Squashed commit of the following:
commit 4f290bdb60
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Wed Feb 13 21:21:30 2013 +0100
Used '0:00' instead of 'UTC' which doesn't always exist in Oracle.
Thanks Ian Kelly for the suggestion.
commit 01b6366f3c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Wed Feb 13 13:38:43 2013 +0100
Made tzname a parameter of datetime_extract/trunc_sql.
This is required to work around a bug in Oracle.
commit 924a144ef8
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Wed Feb 13 14:47:44 2013 +0100
Added support for parameters in SELECT clauses.
commit b4351d2890
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Feb 11 22:30:22 2013 +0100
Documented backwards incompatibilities in the two previous commits.
commit 91ef84713c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Feb 11 09:42:31 2013 +0100
Used QuerySet.datetimes for the admin's date_hierarchy.
commit 0d0de288a5
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Feb 11 09:29:38 2013 +0100
Used QuerySet.datetimes in date-based generic views.
commit 9c0859ff7c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:43:25 2013 +0100
Implemented QuerySet.datetimes on Oracle.
commit 68ab511a4f
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:43:14 2013 +0100
Implemented QuerySet.datetimes on MySQL.
commit 22d52681d3
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:42:29 2013 +0100
Implemented QuerySet.datetimes on SQLite.
commit f6800fd04c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:43:03 2013 +0100
Implemented QuerySet.datetimes on PostgreSQL.
commit 0c829c23f4
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:41:08 2013 +0100
Added datetime-handling infrastructure in the ORM layers.
commit 104d82a777
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Feb 11 10:05:55 2013 +0100
Updated null_queries tests to avoid clashing with the __second lookup.
commit c01bbb3235
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 23:07:41 2013 +0100
Updated tests of .dates().
Replaced .dates() by .datetimes() for DateTimeFields.
Replaced dates with datetimes in the expected output for DateFields.
commit 50fb7a5246
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 21:40:09 2013 +0100
Updated and added tests for QuerySet.datetimes.
commit a8451a5004
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 22:34:46 2013 +0100
Documented the new time lookups and updated the date lookups.
commit 29413eab2b
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Sun Feb 10 16:15:49 2013 +0100
Documented QuerySet.datetimes and updated QuerySet.dates.
For languages with non-breaking space as thousand separator,
standard space input should also be allowed, as few people know
how to enter non-breaking space on keyboards. Refs #17217.
Thanks Alexey Boriskin for the report and initial patch.
Wrap the Parser.compile_filter method call with a try/except and call the
newly added Parser.compile_filter_error(). Overwrite this method in the
DebugParser to throw the correct error.
Since this error was otherwise catched by the compile_function try/except
block the debugger highlighted the wrong line.
The reason was that the except clause needed to remove a connection
from the django.db.connections dict, but other parts of Django do not
expect this to happen. In addition the except clause was silently
swallowing the exception messages.
Refs #19707, special thanks to Carl Meyer for pointing out that this
approach should be taken.
value_annotation isn't very well defined. Before this change, setting it
to datetime.datetime could silently reverse the behavior of isnull
lookups. This commit doesn't have any consequences on the current code.
It's just a safeguard for future ORM hackers.
Previously it was possible to call clear_ordering without the
force_empty argument. The result was that the query was still ordered
by model's meta ordering if that was defined. By making the arg
mandatory it will be easier to spot possible errors caused by assuming
clear_ordering will remove all ordering.
Thanks to Dylan Klomparens for the suggestion. Refs #19720.
When a query had a complex where condition (a condition targeting more
than the base table) a subquery was used for deletion. However, the
query had default ordering from the model's meta and Oracle doesn't
work with ordered subqueries.
The regression was caused by fast-path deletion code introduced in
1cd6e04cd4 for fixing #18676.
Thanks to Dylan Klomparens for the report.
2b5f848207 based its changes on #19061
that made the is_active attribute mandatory for user models.
The try/except was not removed for the groups_for_user function.
refs #19780
Also, according to the comments on the ticket and its duplicates, added
tests execising saving an instance of a model with a GFK to:
* An unsaved object -- This actually doesn't generate the same failure
but another ORM-level exception. The test verifies it's the case.
* An instance of a model with a __nonzero__() method thant returns False
for it. This doesn't fail because that code path isn't executed.
* An instance of a model with a CharField PK and an empty value for it.
This doesn't fail.
Squashed commit of:
commit 508ec9144b35c50794708225b496bde1eb5e60aa
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 22:50:55 2013 +0100
Tweaked default settings file.
* Explained why BASE_DIR exists.
* Added a link to the database configuration options, and put it in its
own section.
* Moved sensitive settings that must be changed for production at the
top.
commit 6515fd2f1aa73a86dc8dbd2ccf512ddb6b140d57
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 14:35:21 2013 +0100
Documented the simplified app & project templates in the changelog.
commit 2c5b576c2ea91d84273a019b3d0b3b8b4da72f23
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 13:59:27 2013 +0100
Minor fixes in tutorials 5 and 6.
commit 55a51531be8104f21b3cca3f6bf70b0a7139a041
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 13:51:11 2013 +0100
Updated tutorial 2 for the new project template.
commit 29ddae87bdaecff12dd31b16b000c01efbde9e20
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 11:58:54 2013 +0100
Updated tutorial 1 for the new project template.
commit 0ecb9f6e2514cfd26a678a280d471433375101a3
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 11:29:13 2013 +0100
Adjusted the default URLconf detection to account for the admin.
It's now enabled by default.
commit 5fb4da0d3d09dac28dd94e3fde92b9d4335c0565
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 10:36:55 2013 +0100
Added security warnings for the most sensitive settings.
commit 718d84bd8ac4a42fb4b28ec93965de32680f091e
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 23:24:06 2013 +0100
Used an absolute path for the SQLite database.
This ensures the settings file works regardless of which directory
django-admin.py / manage.py is invoked from.
BASE_DIR got a +1 from a BDFL and another core dev. It doesn't involve
the concept of a "Django project"; it's just a convenient way to express
relative paths within the source code repository for non-Python files.
Thanks Jacob Kaplan-Moss for the suggestion.
commit 1b559b4bcda622e10909b68fe5cab90db6727dd9
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 23:22:40 2013 +0100
Removed STATIC_ROOT from the default settings template.
It isn't necessary in development, and it confuses beginners to no end.
Thanks Carl Meyer for the suggestion.
commit a55f141a500bb7c9a1bc259bbe1954c13b199671
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 23:21:43 2013 +0100
Removed MEDIA_ROOT/URL from default settings template.
Many sites will never deal with user-uploaded files, and MEDIA_ROOT is
complicated to explain.
Thanks Carl Meyer for the suggestion.
commit 44bf2f2441420fd9429ee9fe1f7207f92dd87e70
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 22:22:09 2013 +0100
Removed logging config.
This configuration is applied regardless of the value of LOGGING;
duplicating it in LOGGING is confusing.
commit eac747e848eaed65fd5f6f254f0a7559d856f88f
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 22:05:31 2013 +0100
Enabled the locale middleware by default.
USE_I18N is True by default, and doesn't work well without
LocaleMiddleware.
commit d806c62b2d00826dc2688c84b092627b8d571cab
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 22:03:16 2013 +0100
Enabled clickjacking protection by default.
commit 99152c30e6a15003f0b6737dc78e87adf462aacb
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 22:01:48 2013 +0100
Reorganized settings in logical sections, and trimmed comments.
commit d37ffdfcb24b7e0ec7cc113d07190f65fb12fb8a
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:54:11 2013 +0100
Avoided misleading TEMPLATE_DEBUG = DEBUG.
According to the docs TEMPLATE_DEBUG works only when DEBUG = True.
commit 15d9478d3a9850e85841e7cf09cf83050371c6bf
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:46:25 2013 +0100
Removed STATICFILES_FINDERS/TEMPLATE_LOADERS from default settings file.
Only developers with special needs ever need to change these settings.
commit 574da0eb5bfb4570883756914b4dbd7e20e1f61e
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:45:01 2013 +0100
Removed STATICFILES/TEMPLATES_DIRS from default settings file.
The current best practice is to put static files and templates in
applications, for easier testing and deployment.
commit 8cb18dbe56629aa1be74718a07e7cc66b4f9c9f0
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:24:16 2013 +0100
Removed settings related to email reporting from default settings file.
While handy for small scale projects, it isn't exactly a best practice.
commit 8ecbfcb3638058f0c49922540f874a7d802d864f
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 18:54:43 2013 +0100
Documented how to enable the sites framework.
commit 23fc91a6fa67d91ddd9d71b1c3e0dc26bdad9841
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:28:59 2013 +0100
Disabled the sites framework by default.
RequestSite does the job for single-domain websites.
commit c4d82eb8afc0eb8568bf9c4d12644272415e3960
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Tue Jan 29 00:08:33 2013 +0100
Added a default admin.py to the application template.
Thanks Ryan D Hiebert for the suggestion.
commit 4071dc771e5c44b1c5ebb9beecefb164ae465e22
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 10:59:49 2013 +0100
Enabled the admin by default.
Everyone uses the admin.
commit c807a31f8d89e7e7fd97380e3023f7983a8b6fcb
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 10:57:05 2013 +0100
Removed admindocs from default project template.
commit 09e4ce0e652a97da1a9e285046a91c8ad7a9189c
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:32:52 2013 +0100
Added links to the settings documentation.
commit 5b8f5eaef364eb790fcde6f9e86f7d266074cca8
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 11:06:54 2013 +0100
Used a significant example for URLconf includes.
commit 908e91d6fcee2a3cb51ca26ecdf12a6a24e69ef8
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 16:22:31 2013 +0100
Moved code comments about WSGI to docs, and rewrote said docs.
commit 50417e51996146f891d08ca8b74dcc736a581932
Author: Aymeric Augustin <aymeric.augustin@m4x.org>
Date: Mon Jan 28 15:51:50 2013 +0100
Normalized the default application template.
Removed the default test that 1 + 1 = 2, because it's been committed
way too many times, in too many projects.
Added an import of `render` for views, because the first view will
often be:
def home(request):
return render(request, "mysite/home.html")
They are handled independently now and the latter can be influenced by
the new BaseCommand.leave_locale_alone internal option.
Thanks chrischambers for the report, Claude, lpiatek, neaf and gabooo for
their work on a patch, originally on refs. #17379.
They are simply ignored now. This allows for a more correct behavior when
they are placed before translatable constructs on the same line.
Previously, the latter were wrongly ignored because the former were
preserved when converting template code to the internal Python-syntax
form later fed to xgettext but Python has no ``/* ... */``-style
comments.
Also, special comments directed to translators are now only taken in
account when they are located at the end of a line. e.g.::
{# Translators: ignored #}{% trans "Literal A" %}{# Translators: valid, associated with "Literal B" below #}
{% trans "Literal B" %}
Behavior of ``{% comment %}...{% endcomment %}``tags remains unchanged.
Thanks juneih at redpill-linpro dot com for the report and Claude for
his work on the issue.
Also:
* Added a ``--no-startup`` option to disable this behavior. Previous
logic to try to execute the code in charge of this funcionality was
flawed (it only tried to do so if the user asked for ipython/bpython
and they weren't found)
* Expand ``~`` in PYTHONSTARTUP value.
Thanks hekevintran at gmail dot com for the report and initial patch.
Refs #3381.
This undocumented method was used in an old version of the admin, is
totally untested and hails from 2008. Although it's listed in the
"public methods" section, as it's not documented or used I don't think
it needs a deprecation path.
If we think it's useful I'll write some tests/docs for it instead...
Thanks a lot to everybody participating in developing this feature.
The patch was developed by multiple people, at least Trac aliases
tonnzor, jimmysong, Fandekasp and slurms.
Stylistic changes added by committer.
The class wasn't used anywhere except in RelatedObject.bind(), which
wasn't used anywhere. The class had one method defined as
NotImplemented, yet the class wasn't subclassed anywhere. In short, the
class was dead code.
It creates a `locale/django.pot` file once instead of one
`locale/<locale_code>/django.pot` file for every locale involved.
Thanks Michal Čihař for the report and patch.
In a normal relational construct, if you're listening for an event
that signals a child was deleted, you dont expect that the parent
was deleted already.
This change ensures that post_delete signals are fired immediately
after objects are deleted in the graph.
The original problem was that queryset cloning was really expensive
when filtering with F() clauses. The __deepcopy__ went too deep copying
_meta attributes of the models used. To fix this the use of
__deepcopy__ in qs cloning was removed.
This commit results in some speed improvements across the djangobench
benchmark suite. Most query_* tests are 20-30% faster, save() is 50%
faster and finally complex filtering situations can see 2x to order
of magnitude improvments.
Thanks to Suor, Alex and lrekucki for valuable feedback.
The guarantee that no queries will be made when accessing results is
done by new EmptyWhere class which is used for query.where and having.
Thanks to Simon Charette for reviewing and valuable suggestions.
When &'ing or |'ing querysets, wrong values could be cached, and crashes
could happen.
Thanks Marc Tamlyn for figuring out the problem and writing the patch.
This allows for a behavior more in line with what is expected by Ipython
users, e.g. the user namespace is initialized from config files, startup
files.
Thanks Benjamin Ragan-Kelley from the IPython dev team for the patch.
The added promotion logic is based on promoting any joins used in only
some of the childs of an OR clause unless the join existed before the
OR clause addition.
The ORM didn't reuse joins for direct foreign key traversals when using
chained filters. For example:
qs.filter(fk__somefield=1).filter(fk__somefield=2))
produced two joins.
As a bonus, reverse onetoone filters can now reuse joins correctly
The regression was caused by the join() method refactor in commit
68847135bc
Thanks for Simon Charette for spotting some issues with the first draft
of the patch.
This is necessary because get_model() checks are case insensitive, and if the swapable check isn't, the
swappable logic gets tied up in knots with models that are partially swapped out.
Thanks to chris@cogdon.org for the report and extensive analysis, and Preston for his work on the draft patch.
Cleaned up the implementation of base convert_values() a little, and
made sure it accepts None as a value for numeric fields.
There are no tests attached. The reason is that not all of the
convert_values() accept None as a value for numeric fields (for example
sqlite3.convert_values()).
The reason the base convert_values() needs to accept None is that this
situation might arise in custom compilers for 3rd party backends. It
is easy to keep the convert_values() working, so lets do that.
This is a rather large refactoring. The "lookup traversal" code was
splitted out from the setup_joins. There is now names_to_path() method
which does the lookup traveling, the actual work of setup_joins() is
calling names_to_path() and then adding the joins found into the query.
As a side effect it was possible to remove the "process_extra"
functionality used by genric relations. This never worked for left
joins. Now the extra restriction is appended directly to the join
condition instead of the where clause.
To generate the extra condition we need to have the join field
available in the compiler. This has the side-effect that we need more
ugly code in Query.__getstate__ and __setstate__ as Field objects
aren't pickleable.
The join trimming code got a big change - now we trim all direct joins
and never trim reverse joins. This also fixes the problem in #10790
which was join trimming in null filter cases.
The trim argument was used by split_exclude() only to trim the last
join from the given lookup. It is cleaner to just trim the last part
from the lookup in split_exclude() directly so that there is no need
to burden add_filter() with the logic needed for only split_exclude().
This makes it easier to make a ModelBackend-compliant (with regards to
permissions) User model.
Thanks to cdestigter for the report about the relationship between
ModelBackend and permissions, and to the many users on django-dev that
contributed to the discussion about mixins.