#31185: UniqueConstraint rises fields.E310 error because of issue with no
backward
compatibility with unique_together
-------------------------------------+-------------------------------------
Reporter: Pavel | Owner: nobody
Type: Bug | Status: new
Component: | Version: 2.2
Migrations | Keywords: UniqueConstraint,
Severity: Normal | unique_together
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Hello,
I'm trying to create migration with this kind of model.
{{{
class AppUsers(models.Model):
name = models.CharField(...)
uid = models.CharField(...)
source = models.ForeignKey(...)
class Meta:
constraints = [models.UniqueConstraint(fields=['uid', 'source'],
name='appusers_uniqueness')]
}}}
When I start ''makemigrations'' command in manage.py I've faced
fields.E310 [https://docs.djangoproject.com/en/2.2/ref/checks/#related-
fields] error
It says that I should add unique_together field in Meta options:
**app_name.AppUsers.field: (fields.E310) No subset of the fields 'uid',
'source' on model 'AppUsers' is unique.
HINT: Add unique=True on any of those fields or add at least a subset of
them to a unique_together constraint.**
If I change Meta options to unique_together constraint migration passes
with no errors.
{{{
class AppUsers(models.Model):
name = models.CharField(...)
uid = models.CharField(...)
source = models.ForeignKey(...)
class Meta:
unique_together = [['uid', 'source']]
}}}
As mentioned in docs
[https://docs.djangoproject.com/en/2.2/ref/models/options/#unique-
together] ''unique_together'' may be deprecated in the future. So I think
nobody wants to face this issue when this will be deprecated :)
Thanks,
Pavel
--
Ticket URL: <https://code.djangoproject.com/ticket/31185>
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