Handle empty data with serializer (#4564)

rest_framework/serializers.py

@@ -507,6 +507,11 @@ class Serializer(BaseSerializer):
     @property
     def errors(self):
         ret = super(Serializer, self).errors
+        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+            # Edge case. Provide a more descriptive error than
+            # "this field may not be null", when no data is passed.
+            detail = ErrorDetail('No data provided', code='null')
+            ret = {api_settings.NON_FIELD_ERRORS_KEY: [detail]}
         return ReturnDict(ret, serializer=self)
 
 
@@ -700,6 +705,11 @@ class ListSerializer(BaseSerializer):
     @property
     def errors(self):
         ret = super(ListSerializer, self).errors
+        if isinstance(ret, list) and len(ret) == 1 and ret[0].code == 'null':
+            # Edge case. Provide a more descriptive error than
+            # "this field may not be null", when no data is passed.
+            detail = ErrorDetail('No data provided', code='null')
+            ret = {api_settings.NON_FIELD_ERRORS_KEY: [detail]}
         if isinstance(ret, dict):
             return ReturnDict(ret, serializer=self)
         return ReturnList(ret, serializer=self)

tests/test_serializer.py

@@ -62,6 +62,12 @@ class TestSerializer:
         with pytest.raises(AssertionError):
             serializer.save()
 
+    def test_validate_none_data(self):
+        data = None
+        serializer = self.Serializer(data=data)
+        assert not serializer.is_valid()
+        assert serializer.errors == {'non_field_errors': ['No data provided']}
+
 
 class TestValidateMethod:
     def test_non_field_error_validate_method(self):

tests/test_serializer_nested.py

@@ -41,6 +41,12 @@ class TestNestedSerializer:
         serializer = self.Serializer()
         assert serializer.data == expected_data
 
+    def test_nested_serialize_no_data(self):
+        data = None
+        serializer = self.Serializer(data=data)
+        assert not serializer.is_valid()
+        assert serializer.errors == {'non_field_errors': ['No data provided']}
+
 
 class TestNotRequiredNestedSerializer:
     def setup(self):