#20301: Unique field validation with multiple DB connections.
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Reporter: SardarNL | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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`django.db.models.base._perform_unique_checks` is not using
`self._state.db` to lookup unique fields. Check the following:
{{{
class MyModel(models.Model):
my_unique = models.IntegerField(unique=True)
obj = MyModel(my_unique=value_exists_on_default_new_on_other_connection)
obj._state.db = other_connection
obj.full_clean()
# for existing objects _state.db will be already set
obj = MyModel.objects.using(other_connection).get(pk=existing)
obj.my_unique = value_exists_on_default_new_on_other_connection
obj.full_clean()
}}}
`full_clean()` will `validate_unique()` -> `_perform_unique_checks()`,
which will eventually `qs =
model_class._default_manager.filter(**lookup_kwargs)`. The default manager
is always using default connection, so unique check will be performed on
default connection. Other validators, such as ForeignKey lookup, properly
use `.using()` to keep talking to the database where the object came from.
Fix: {{{ qs =
model_class._default_manager.filter(**lookup_kwargs).using(self._state.db)
}}}
The same fix is needed for `_perform_date_checks()`.
--
Ticket URL: <https://code.djangoproject.com/ticket/20301>
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