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.
select_related('foo').select_related('bar') is now equivalent to
select_related('foo', 'bar').
Also reworded docs to recommend select_related(*fields) over select_related()
Sphinx generates left single quotes for apostrophes after
code markup, when right single quotes are required. The
easiest way to fix this is just by inserting the unicode
character for a right single quote.
Instances of the problem were found by looking for
">‘" in the generated HTML.
Additionally this patch solves the orthogonal problem that specialized
`QuerySet` like `ValuesQuerySet` didn't inherit from the current `QuerySet`
type. This wasn't an issue until now because we didn't officially support
custom `QuerySet` but it became necessary with the introduction of this new
feature.
Thanks aaugustin, akaariai, carljm, charettes, mjtamlyn, shaib and timgraham
for the reviews.
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.
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.
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 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.
This is the start of a deprecation path for the depth kwarg on
select_related. Removing this will allow us to update select_related so
it chains properly and have an API similar to prefetch_related.
Thanks to Marc Tamlyn for spearheading and initial patch.
refs #16855
