#20625: Custom Chainable QuerySets
-------------------------------------+-------------------------------------
Reporter: danols | Owner: danols
Type: New feature | Status: assigned
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: QuerySet, | Needs documentation: 1
models.Manager, chainable | Patch needs improvement: 1
Has patch: 1 | UI/UX: 0
Needs tests: 1 |
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Changes (by loic84):
* needs_better_patch: 0 => 1
* needs_tests: 0 => 1
* needs_docs: 0 => 1
Comment:
I've tried to come up with a strategy to deprecate all the legacy proxy
methods.
The issue at hand is custom managers in the wild that call `super` in
overridden methods.
@charettes mentioned on IRC that `__getattribute__` would enable calls to
`super` but that we wouldn’t be able to differentiate a normal access
(which shouldn't go through the legacy method) and calls to `super` which
should trigger the deprecation warning.
We could have a metaclass, similar to `RenameMethodsBase` which adds back
legacy methods for every method with the same name in the MRO: if our
method is ever called (by `super`) we trigger the deprecation warning.
I ran into a problem when trying to deprecate `Manager.create()` and
`Manager.get_or_create()` with `RelatedManager` (and similar):
https://gist.github.com/loic/5861660
https://github.com/django/django/blob/master/tests/multiple_database/tests.py#L907-L921
If `RelatedManager` doesn't call ` super`, we'll never reach custom
managers' `create()` and `get_or_create()`. I don't see a solution to that
other than making a backward incompatible change. Or we could elect a few
proxy methods that shouldn’t be deprecated (like `Manager.all()`, see
comment in the patch).
Any suggestions?
If we can't reach consensus on the deprecation plan I suggest we move on
with this ticket and open a new one regarding the deprecation itself.
--
Ticket URL: <https://code.djangoproject.com/ticket/20625#comment:15>
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