many=True, allow_null=True allows null instead of the list, not nulls in the list.

rest_framework/serializers.py

@@ -50,7 +50,7 @@
 LIST_SERIALIZER_KWARGS = (
     'read_only', 'write_only', 'required', 'default', 'initial', 'source',
     'label', 'help_text', 'style', 'error_messages', 'allow_empty',
-    'instance', 'data', 'partial', 'context'
+    'instance', 'data', 'partial', 'context', 'allow_null'
 )
 
 

tests/test_serializer_nested.py

@@ -69,3 +69,59 @@ def test_multipart_validate(self):
         input_data = QueryDict('nested[one]=1')
         serializer = self.Serializer(data=input_data)
         assert serializer.is_valid()
+
+
+class TestNestedSerializerWithMany:
+    def setup(self):
+        class NestedSerializer(serializers.Serializer):
+            example = serializers.IntegerField(max_value=10)
+
+        class TestSerializer(serializers.Serializer):
+            allow_null = NestedSerializer(many=True, allow_null=True)
+            not_allow_null = NestedSerializer(many=True)
+
+        self.Serializer = TestSerializer
+
+    def test_null_allowed_if_allow_null_is_set(self):
+        input_data = {
+            'allow_null': None,
+            'not_allow_null': [{'example': '2'}, {'example': '3'}]
+        }
+        expected_data = {
+            'allow_null': None,
+            'not_allow_null': [{'example': 2}, {'example': 3}]
+        }
+        serializer = self.Serializer(data=input_data)
+
+        assert serializer.is_valid(), serializer.errors
+        assert serializer.validated_data == expected_data
+
+    def test_null_is_not_allowed_if_allow_null_is_not_set(self):
+        input_data = {
+            'allow_null': None,
+            'not_allow_null': None
+        }
+        serializer = self.Serializer(data=input_data)
+
+        assert not serializer.is_valid()
+
+        expected_errors = {'not_allow_null': [serializer.error_messages['null']]}
+        assert serializer.errors == expected_errors
+
+    def test_run_the_field_validation_even_if_the_field_is_null(self):
+        class TestSerializer(self.Serializer):
+            validation_was_run = False
+
+            def validate_allow_null(self, value):
+                TestSerializer.validation_was_run = True
+                return value
+
+        input_data = {
+            'allow_null': None,
+            'not_allow_null': [{'example': 2}]
+        }
+        serializer = TestSerializer(data=input_data)
+
+        assert serializer.is_valid()
+        assert serializer.validated_data == input_data
+        assert TestSerializer.validation_was_run