Support save() on list serializers (fixes #75)

rest_framework_dataclasses/serializers.py

@@ -665,6 +665,44 @@ def validated_data(self) -> T:
 
 
 class DataclassListSerializer(rest_framework.serializers.ListSerializer, Generic[T]):
+ # Type hints for (private) fields on the parent class
+ _validated_data: List[T]
+
+ def save(self, **kwargs: KWArgs) -> T:
+ assert hasattr(self, '_errors'), (
+ "You must call `.is_valid()` before calling `.save()`."
+ )
+
+ assert not self.errors, (
+ "You cannot call `.save()` on a serializer with invalid data."
+ )
+
+ assert not hasattr(self, '_data'), (
+ "You cannot call `.save()` after accessing `serializer.data`."
+ "If you need to access data before committing to the dataclass then "
+ "inspect 'serializer.validated_data' instead. "
+ )
+
+ # Explicitly use the internal validated_data here, as the empty sentinel values must not be stripped yet. Do not
+ # use dataclasses.replace(), as it doesn't handle non-init fields properly.
+ validated_data = []
+ for item in self._validated_data:
+ obj = copy.deepcopy(item)
+ for field, value in kwargs.items():
+ setattr(obj, field, value)
+ validated_data.append(obj)
+
+ if self.instance is not None:
+ self.instance = self.update(self.instance, validated_data)
+ else:
+ self.instance = self.create(validated_data)
+
+ assert self.instance is not None, (
+ '`update()` or `create()` did not return an object instance.'
+ )
+
+ return self.instance
+
  @cached_property
  def validated_data(self) -> List[T]:
  """

tests/test_issues.py

@@ -116,3 +116,18 @@ class A:
 
  self.assertEqual(instance.foo, 'abc')
  self.assertEqual(instance.bar, 'def')
+
+ # Issue #75: save() on list serializer doesn't work
+ def test_list_save(self):
+ @dataclasses.dataclass
+ class Foo:
+ name: str
+
+ serializer = DataclassSerializer(dataclass=Foo, many=True, data=[{'name': 'bar'}, {'name': 'baz'}])
+ serializer.is_valid(raise_exception=True)
+ items = serializer.save()
+
+ self.assertIsInstance(items, list)
+ self.assertEqual(len(items), 2)
+ self.assertEqual(items[0], Foo('bar'))
+ self.assertEqual(items[1], Foo('baz'))