How to serialize snake_case model fields to camelCase in django rest framework

Question

I'm adding REST API endpoints to my existing Django application. I'm using DRF ModelSerializer. My model classes follow the pep8 naming convention and use snake_case for field names, but I need the JSON response to be in camelCase. How can I achieve that in a cross-cutting way without defining proxy fields on each of my serializers?

Answer 1

You could generate a mixin that patches the .to_representation() method of all the top-level serializers:

class CamelCaseMixin:
    def to_representation(self, *args, **kwargs):
        return to_camelcase_data(super().to_representation(*args, **kwargs))

    def to_internal_value(self, data):
        return super().to_internal_value(to_snake_case_data(data))

with as helper functions to convert between camelCase and snake_case:

import re

CAMEL_REGEX = re.compile('(?<=.)_(\\w)')
SNAKE_REGEX = re.compile('(?<=[a-z])([A-Z])')


def match_upper(match):
    return match.group(1).upper()


def match_snake(match):
    return f'_{match.group(1).lower()}'


def to_camelcase(text):
    return CAMEL_REGEX.sub(match_upper, text)


def to_snake_case(text):
    return SNAKE_REGEX.sub(match_snake, text)


def to_camelcase_data(data):
    if isinstance(data, dict):
        return {to_camelcase(k): to_camelcase_data(v) for k, v in data.items()}
    elif isinstance(data, list):
        return [to_camelcase_data(datum) for datum in data]
    else:
        return data


def to_snake_case_data(data):
    if isinstance(data, dict):
        return {to_snake_case(k): to_snake_case_data(v) for k, v in data.items()}
    elif isinstance(data, list):
        return [to_snake_case_data(datum) for datum in data]
    else:
        return data

So you can define a model serializer:

class MyModelSerializer(CamelCaseMixin, serializers.ModelSerializer):
    class Meta:
        model = MyModel
        fields = ['my_field1', 'my_field2']

and then plug in this as serializer for the APIViews and ViewSets.