Opened 6 years ago
Last modified 6 years ago
#29466 new Bug
Textual "to" parameter of ForeignKey fails to resolve if placed in abstract model
Reported by: | Vitalik Verhovodov | Owned by: | nobody |
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Component: | Database layer (models, ORM) | Version: | 2.0 |
Severity: | Normal | Keywords: | |
Cc: | Triage Stage: | Accepted | |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
import django from django.conf import settings settings.configure(DEBUG=True) django.setup() from django.db import models SHOULD_I_FAIL = True # switch this to reproduce the bug class ReferencedModel(models.Model): field = models.FloatField() class Meta: app_label = 'myapp' ref = 'ReferencedModel' if SHOULD_I_FAIL else ReferencedModel class AbstractModel(models.Model): # NOTE: only abstract models are affected field = models.ForeignKey(ref, on_delete=models.CASCADE) class Meta: abstract = True app_label = 'myapp' class RealModel(AbstractModel): other_field = models.CharField(max_length=100) class Meta: app_label = 'myapp' ffield = AbstractModel._meta.get_field('field') # ValueError: Related model 'ReferencedModel' cannot be resolved print(ffield.target_field)
Change History (3)
comment:1 by , 6 years ago
Triage Stage: | Unreviewed → Accepted |
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comment:2 by , 6 years ago
I will assume that this is intended behavior. According to #24215, abstract models does not register pending lookups into Apps registry. I have tried to implement it, but found an issue with recursive relations in abstract model - they cannot be resolved (because abstract models is not registered), but it is valid to have them, because they can be resolved in concrete children classes. So for abstract models lazy-referenced relations should not be resolved. I am not sure about this, need someone more proficient to take a look.
comment:3 by , 6 years ago
Sounds reasonable, but what if I'm sure that all models are already loaded (e.g. during Command execution)? How can I manually resolve textual model name and target_field?
Reproduced at 741792961815cf4a95c5ce8ab590dfc7700c6153.