Issue:

Adding the following test to TestUniqueConstraintValidation demonstrates an issue in the serializer’s unique constraint validation logic:

deftest_unique_constraint_create(self):classSourceUniqueConstraintSerializer(serializers.ModelSerializer):raceName=serializers.CharField(source="race_name")classMeta:model=UniqueConstraintModelfields= ("raceName","position","global_id","fancy_conditions")UniqueConstraintModel.objects.exclude(pk=self.instance.pk).delete()data= {"race_name":"other","position":1,"global_id":3,"fancy_conditions":1,    }obj=UniqueConstraintModel.objects.create(**data)obj.delete()serializer=SourceUniqueConstraintSerializer(data=data)assertserializer.is_valid()# This unexpectedly fails

• Creating a UniqueConstraintModel instance directly with UniqueConstraintModel.objects.create() succeeds, indicating no unique constraint violation occurs at the database level.
• However, validating the same data through the ModelSerializer fails.

Root cause:
The unique validator used by the serializer does not account for theglobal_id field during validation offancy_conditions, even thoughglobal_id is part of the conditional logic in the unique constraint.

As a result, the validation incorrectly identifies a conflict based only onfancy_conditions, without considering that theglobal_id in the input data should exempt it from the constraint.

Expected behavior:

Serializer validation should succeed in this case, consistent with the model-level behavior.