Fix UniqueTogetherValidator for NULL values

rest_framework/validators.py

@@ -138,7 +138,9 @@ class UniqueTogetherValidator:
         queryset = self.queryset
         queryset = self.filter_queryset(attrs, queryset)
         queryset = self.exclude_current_instance(attrs, queryset)
-        if queryset.exists():
+
+        # Ignore validation if any field is None
+        if None not in attrs.values() and queryset.exists():
             field_names = ', '.join(self.fields)
             raise ValidationError(self.message.format(field_names=field_names))
 

tests/test_validators.py

@@ -76,8 +76,8 @@ class TestUniquenessValidation(TestCase):
 # -----------------------------------
 
 class UniquenessTogetherModel(models.Model):
-    race_name = models.CharField(max_length=100)
-    position = models.IntegerField()
+    race_name = models.CharField(max_length=100, null=True)
+    position = models.IntegerField(null=True)
 
     class Meta:
         unique_together = ('race_name', 'position')
@@ -108,8 +108,8 @@ class TestUniquenessTogetherValidation(TestCase):
         expected = dedent("""
             UniquenessTogetherSerializer():
                 id = IntegerField(label='ID', read_only=True)
-                race_name = CharField(max_length=100, required=True)
-                position = IntegerField(required=True)
+                race_name = CharField(allow_null=True, max_length=100, required=True)
+                position = IntegerField(allow_null=True, required=True)
                 class Meta:
                     validators = [<UniqueTogetherValidator(queryset=UniquenessTogetherModel.objects.all(), fields=('race_name', 'position'))>]
         """)
@@ -178,10 +178,20 @@ class TestUniquenessTogetherValidation(TestCase):
         expected = dedent("""
             ExcludedFieldSerializer():
                 id = IntegerField(label='ID', read_only=True)
-                race_name = CharField(max_length=100)
+                race_name = CharField(allow_null=True, max_length=100, required=False)
         """)
         assert repr(serializer) == expected
 
+    def test_ignore_validation_for_null_fields(self):
+        UniquenessTogetherModel.objects.create(
+            race_name=None,
+            position=None
+        )
+        data = {'race_name': None, 'position': None}
+        serializer = UniquenessTogetherSerializer(data=data)
+
+        assert serializer.is_valid()
+
 
 # Tests for `UniqueForDateValidator`
 # ----------------------------------