Fix unique together validator doesn't respect condition's fields

rest_framework/serializers.py

@@ -1430,15 +1430,18 @@ def get_unique_together_constraints(self, model):
         """
         for parent_class in [model] + list(model._meta.parents):
             for unique_together in parent_class._meta.unique_together:
-                yield unique_together, model._default_manager
+                yield unique_together, model._default_manager, []
             for constraint in parent_class._meta.constraints:
                 if isinstance(constraint, models.UniqueConstraint) and len(constraint.fields) > 1:
-                    yield (
-                        constraint.fields,
-                        model._default_manager
-                        if constraint.condition is None
-                        else model._default_manager.filter(constraint.condition)
-                    )
+                    if constraint.condition is None:
+                        queryset = model._default_manager
+                        condition_fields = []
+                    else:
+                        queryset = model._default_manager.filter(constraint.condition)
+                        condition_fields = [
+                            f[0].split("__")[0] for f in constraint.condition.children
+                        ]
+                    yield (constraint.fields, queryset, condition_fields)
 
     def get_uniqueness_extra_kwargs(self, field_names, declared_fields, extra_kwargs):
         """
@@ -1470,9 +1473,9 @@ def get_uniqueness_extra_kwargs(self, field_names, declared_fields, extra_kwargs
 
         # Include each of the `unique_together` and `UniqueConstraint` field names,
         # so long as all the field names are included on the serializer.
-        for unique_together_list, queryset in self.get_unique_together_constraints(model):
-            if set(field_names).issuperset(unique_together_list):
-                unique_constraint_names |= set(unique_together_list)
+        for unique_together_list, queryset, condition_fields in self.get_unique_together_constraints(model):
+            if set(field_names).issuperset((*unique_together_list, *condition_fields)):
+                unique_constraint_names |= set((*unique_together_list, *condition_fields))
 
         # Now we have all the field names that have uniqueness constraints
         # applied, we can add the extra 'required=...' or 'default=...'
@@ -1592,12 +1595,12 @@ def get_unique_together_validators(self):
         # Note that we make sure to check `unique_together` both on the
         # base model class, but also on any parent classes.
         validators = []
-        for unique_together, queryset in self.get_unique_together_constraints(self.Meta.model):
+        for unique_together, queryset, condition_fields in self.get_unique_together_constraints(self.Meta.model):
             # Skip if serializer does not map to all unique together sources
-            if not set(source_map).issuperset(unique_together):
+            if not set(source_map).issuperset((*unique_together, *condition_fields)):
                 continue
 
-            for source in unique_together:
+            for source in (*unique_together, *condition_fields):
                 assert len(source_map[source]) == 1, (
                     "Unable to create `UniqueTogetherValidator` for "
                     "`{model}.{field}` as `{serializer}` has multiple "
@@ -1614,9 +1617,9 @@ def get_unique_together_validators(self):
                 )
 
             field_names = tuple(source_map[f][0] for f in unique_together)
+            condition_fields = tuple(source_map[f][0] for f in condition_fields)
             validator = UniqueTogetherValidator(
-                queryset=queryset,
-                fields=field_names
+                queryset=queryset, fields=field_names, condition_fields=condition_fields
             )
             validators.append(validator)
         return validators

rest_framework/validators.py

@@ -99,10 +99,11 @@ class UniqueTogetherValidator:
     missing_message = _('This field is required.')
     requires_context = True
 
-    def __init__(self, queryset, fields, message=None):
+    def __init__(self, queryset, fields, message=None, condition_fields=None):
         self.queryset = queryset
         self.fields = fields
         self.message = message or self.message
+        self.condition_fields = [] if condition_fields is None else condition_fields
 
     def enforce_required_fields(self, attrs, serializer):
         """
@@ -114,7 +115,7 @@ def enforce_required_fields(self, attrs, serializer):
 
         missing_items = {
             field_name: self.missing_message
-            for field_name in self.fields
+            for field_name in (*self.fields, *self.condition_fields)
             if serializer.fields[field_name].source not in attrs
         }
         if missing_items:
@@ -127,7 +128,7 @@ def filter_queryset(self, attrs, queryset, serializer):
         # field names => field sources
         sources = [
             serializer.fields[field_name].source
-            for field_name in self.fields
+            for field_name in (*self.fields, *self.condition_fields)
         ]
 
         # If this is an update, then any unprovided field should

tests/test_validators.py

@@ -513,6 +513,11 @@ class Meta:
                 name="unique_constraint_model_together_uniq",
                 fields=('race_name', 'position'),
                 condition=models.Q(race_name='example'),
+            ),
+            models.UniqueConstraint(
+                name="unique_constraint_model_together_uniq2",
+                fields=('race_name', 'position'),
+                condition=models.Q(fancy_conditions__gte=10),
             )
         ]
 
@@ -563,13 +568,59 @@ def test_unique_together_field(self):
         to UniqueTogetherValidator as fields and queryset
         """
         serializer = UniqueConstraintSerializer()
-        assert len(serializer.validators) == 1
+        assert len(serializer.validators) == 2
         validator = serializer.validators[0]
         assert validator.fields == ('race_name', 'position')
         assert set(validator.queryset.values_list(flat=True)) == set(
             UniqueConstraintModel.objects.filter(race_name='example').values_list(flat=True)
         )
 
+    def test_unique_together_condition(self):
+        """
+        Fields used in UniqueConstraint's condition must be included
+        into queryset existence check
+        """
+        UniqueConstraintModel.objects.create(
+            race_name='condition',
+            position=1,
+            global_id=10,
+            fancy_conditions=10
+        )
+        serializer = UniqueConstraintSerializer(data={
+            'race_name': 'condition',
+            'position': 1,
+            'global_id': 11,
+            'fancy_conditions': 9,
+        })
+        assert serializer.is_valid()
+        serializer = UniqueConstraintSerializer(data={
+            'race_name': 'condition',
+            'position': 1,
+            'global_id': 11,
+            'fancy_conditions': 11,
+        })
+        assert not serializer.is_valid()
+
+    def test_unique_together_condition_fields_required(self):
+        """
+        Fields used in UniqueConstraint's condition must be present in serializer
+        """
+        serializer = UniqueConstraintSerializer(data={
+            'race_name': 'condition',
+            'position': 1,
+            'global_id': 11,
+        })
+        assert not serializer.is_valid()
+        assert serializer.errors == {'fancy_conditions': ['This field is required.']}
+
+        class NoFieldsSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = UniqueConstraintModel
+                fields = ('race_name', 'position', 'global_id')
+
+        serializer = NoFieldsSerializer()
+        assert len(serializer.validators) == 1
+
     def test_single_field_uniq_validators(self):
         """
         UniqueConstraint with single field must be transformed into
@@ -579,7 +630,7 @@ def test_single_field_uniq_validators(self):
         extra_validators_qty = 2 if django_version[0] >= 5 else 0
         #
         serializer = UniqueConstraintSerializer()
-        assert len(serializer.validators) == 1
+        assert len(serializer.validators) == 2
         validators = serializer.fields['global_id'].validators
         assert len(validators) == 1 + extra_validators_qty
         assert validators[0].queryset == UniqueConstraintModel.objects