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TypeError with partial=True

See original GitHub issue

MR #18 created a new issue.

Consider this simple serializer:

class MyPolymorphicSerializer(PolymorphicSerializer):
    pass  # Mostly irrelevant

class MySerializer(Serializer):
    foo = CharField()
    bar = MyPolymorphicSerializer(required=false)

I use standard DRF viewsets to do a PATCH request (i.e. serializer has partial=True) to an endpoint using MySerializer, with JSON content: {"foo": "my_foo"}. We exclude bar, which for PATCH requests should mean that this field is virtually ignored and kept as it is before the request. This worked as expected before this MR.

Now however, it will raise this error:

  File "/usr/local/lib/python3.8/site-packages/rest_framework/mixins.py", line 67, in update
    serializer.is_valid(raise_exception=True)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/serializers.py", line 234, in is_valid
    self._validated_data = self.run_validation(self.initial_data)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/serializers.py", line 433, in run_validation
    value = self.to_internal_value(data)
  File "/usr/local/lib/python3.8/site-packages/rest_framework/serializers.py", line 490, in to_internal_value
    validated_value = field.run_validation(primitive_value)
  File "/usr/local/lib/python3.8/site-packages/rest_polymorphic/serializers.py", line 95, in run_validation
    resource_type = self._get_resource_type_from_mapping(data)
  File "/usr/local/lib/python3.8/site-packages/rest_polymorphic/serializers.py", line 112, in _get_resource_type_from_mapping
    return mapping[self.resource_type_field_name]
TypeError: 'type' object is not subscriptable

This happens because normally, Serializer.run_validation does checks (validate_empty_values) to ensure there is some data to begin with. Now however, it tries to determine the resource_type before running the base implementation. When determining the resource_type, it tries to do empty['somekey'], which of course results in a TypeError.

Note that there might be other similar edge-cases I didn’t cover here.

IMO this issue is more critical than the one solved by #18 in the first place.

Issue Analytics

State:
Created 3 years ago
Comments:7 (4 by maintainers)

Top GitHub Comments

10reactions

denisorehovskycommented, May 6, 2020

Hi. Thanks. I haven’t used this library for a long time and I’m not interested in doing any fixes right now. If you have some free time, you can send a PR if you want. I will take a look. Thanks

3reactions

iglosiggiocommented, May 6, 2020

I’m not working w/DRF nor django-polymorphic rigth now. Is there any reason why adding a check for empty data on my previous PR wouldn’t fix your problem?

I’ll try to come up with a fix later 😃

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