Automatically use correct auto-manager class for inherited models
|Reported by:||Malcolm Tredinnick||Owned by:||Malcolm Tredinnick|
|Component:||Database layer (models, ORM)||Version:||master|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
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 Changed 8 years ago by
|Summary:||Understand correct auto-manager class for inherited models → Automatically use correct auto-manager class for inherited models|
|Triage Stage:||Unreviewed → Accepted|