fields.E310-E311 should take into account UniqueConstraints without conditions.

[Pavel Garkin]

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

[Mariusz Felisiak]

Agreed, both checks should take into UniqueConstraint's without condition's.

[Ahmad Abdallah]

Posting a patch soon

[Ahmad Abdallah]

​Patch submitted. Let me know what i need to improve. I haven't written a test it but I tested it on the code snippet posted above and it worked

[Mariusz Felisiak <felisiak.mariusz@…>]

In 5bf28ac2:

Fixed #31185 -- Fixed detecting of unique fields in ForeignKey/ForeignObject checks when using Meta.constraints.