Issue:

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

def test_unique_constraint_create(self): class SourceUniqueConstraintSerializer(serializers.ModelSerializer): raceName = serializers.CharField(source="race_name") class Meta: model = UniqueConstraintModel fields = ("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) assert serializer.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 the global_id field during validation of fancy_conditions, even though global_id is part of the conditional logic in the unique constraint.

As a result, the validation incorrectly identifies a conflict based only on fancy_conditions, without considering that the global_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.