3.15 regression: Serializer validation failed for unique together constraint #9358
Description
The new 3.15.0 release introduced a bug with validation unique constraint.
Code to reproduce an error:
from django.db import models from rest_framework import serializers class Pet(models.Model): name = models.CharField(max_length=100) animal_type = models.CharField(max_length=100) can_fly = models.BooleanField(null=True) class Meta: constraints = ( UniqueConstraint( fields=["name", "animal_type"], name="unique_pet", condition=Q(can_fly__isnull=True), ), ) class PetSerializer(serializers.ModelSerializer): class Meta: model = Pet fields = ('name', 'animal_type', 'can_fly') Pet.objects.create(animal_type='dog', name='Fluffy', can_fly=None) serializer = PetSerializer(data={ 'can_fly': False, 'animal_type': 'dog', 'name': 'Fluffy' }) serializer.is_valid(raise_exception=True) The last line raises the error:
Error Traceback (most recent call last): rest_framework.exceptions.ValidationError: { 'non_field_errors': [ErrorDetail(string='The fields name, animal_type must make a unique set.', code='unique')] } Validation ignores that can_fly field is present in the serializer.initial_data and just runs UniqueTogetherValidator for animal_type and name fields.