drf-payload-customizer

drf-payload-customizer

This package allows you to customize your django-rest-framework serializer i/o to make modern frontend frameworks happy. The following modifications are supported:

• Transformation: Convert all keys in API output to camelCase. Also on reception of an input on an API, transform all inputs to snake_case.
• Translation: Rename a key in your API schema. (works in both direction).
• Nullify/Balankify: Replace "" with None on output direction and vice versa in the other direction.

We introduce 3 seperate Mixins that can you can subclass your APIView from to achieve 1-3. They are:

• PayloadTransformationMixin: Perform transformation (1) above. Has an optional parameter PAYLOAD_TRANSFORM_NESTED (see tests) which you can set to True in your Serializer.Meta class to recursively convert all nested dictionaries. This feature only works in the output direction.
• PayloadTranslationMixin: Perform translation (2) above. You can specify custom mappings using a field_mappings dict in your Serializer.Meta class.
• PayloadNoNullOrNoneMixin: Perform nullify/blankify (3) above.

Requirements

The mixin requires you to have the following dependencies:

djangorestframework==3.8.2

We are positive it would work with other versions of Django Rest Framework as well. However, you will require Django==2.1.2 to run the unit tests.

Use it in your project

You can use all three of the mixins together like this in your project using our drf_payload_customizer.mixins.PayloadConverterMixin mixin. The mixin performs (1-3) modifications listed above. Here is how it is implemented:

class PayloadConverterMixin(PayloadTransformationMixin,
                            PayloadTranslationMixin,
                            PayloadNoNullOrNoneMixin):
    """
    Use this mixin in all of our Serializers, to convert the JSON into a
    format that is easier consumed by modern front-ends.
    """

    def to_representation(self, instance):
        return super().to_representation(instance)

    def to_internal_value(self, camel_cased):
        return super().to_internal_value(camel_cased)

Now, subclass your APIViews with PayloadConverterMixin as given below:

from drf_payload_customizer.mixins import PayloadConverterMixin

class CustomTestModelSerializer(PayloadConverterMixin, ModelSerializer):
    class Meta:
        model = TestModel
        fields = ('parama', 'param_b',)
        PAYLOAD_TRANSFORM_NESTED = True
        # The mapping is the snake_case of your expected o/p
        field_mappings = {
            'parama': 'param_a' 
        }
        
# Now your serializer would output: 
test_serializer = CustomTestModelSerializer(obj)
JSONRenderer().render(test_serializer.data)
> {'paramA': '', 'paramB': None}

# Your serializer also admits input in the same format: 
content = json.dumps({'paramA': 'testA', 'paramB': 3}).encode()
stream = BytesIO(content)
data = JSONParser().parse(stream)
serializer = CustomTestModelSerializer(data=data)
self.assertTrue(serializer.is_valid())
> True

To run tests

cd drf_payload_customizer
# Make sure you change to a virutal environment according to your project setup
python setup.py install 
pip install -r requirements.txt 
cd tests/test_app/ 
python manage.py test