Opened 16 years ago
Closed 8 years ago
#10506 closed Bug (fixed)
Automatically use correct auto-manager class for inherited models
Reported by: | Malcolm Tredinnick | Owned by: | Malcolm Tredinnick |
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Component: | Database layer (models, ORM) | Version: | dev |
Severity: | Normal | Keywords: | use_for_related_fields |
Cc: | Triage Stage: | Accepted | |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
When creating a subclass of a model with a default manager that has use_for_related_fields = True
, and if the subclass has no explicit manager set, we should use the class of the parent's manager. This is consistent with every other time we create an automatic manager (in fact, the docs added in r10057 hint that we already do this, but it's not quite true for subclasses yet).
For multiple base classes, we walk them all and choose the most derived manager satisfying this constraint. It should subclass all the other managers that also do. If there is no such manager (e.g. two different managers subclassing django.db.models.Manager
), we raise an error and the user has to specify the default manager themselves. This is because there would be no way to ensure that an appropriate get_query_set()
method id used
Using MRO to determine the class type is wrong, since a model that inherits from both an ordinary model and a gis model, in that order, needs a GeoManager (which already subclasses Manager, so we're fine).
When this is done, there's a "TODO" in the gis tests that can be removed, too (in a child model).
I'll get to this before 1.1, but I had to fix the first parts of this as part of some other yak-shaving and don't want to get distracted on this yet.
Change History (9)
comment:1 by , 16 years ago
Summary: | Understand correct auto-manager class for inherited models → Automatically use correct auto-manager class for inherited models |
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Triage Stage: | Unreviewed → Accepted |
comment:2 by , 16 years ago
milestone: | 1.1 |
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comment:3 by , 14 years ago
Severity: | → Normal |
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Type: | → Bug |
comment:6 by , 9 years ago
Replying to mtredinnick:
When creating a subclass of a model with a default manager that has
use_for_related_fields = True
, and if the subclass has no explicit manager set, we should use the class of the parent's manager.
I don't think that child class should inherit parent class's manager since documentation says it shouldn't: https://docs.djangoproject.com/en/dev/topics/db/managers/#custom-managers-and-model-inheritance
comment:7 by , 9 years ago
Keywords: | use_for_related_fields added |
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comment:8 by , 8 years ago
PR6175 revamps manager inheritance and allows choosing the default manager explicitly through the base_manager_name
model option.
Given the work to do before 1.1, pushing this one to later.