known_fields_mixin.py

from rest_framework import serializers
from rest_framework.fields import empty
from rest_framework.settings import api_settings


empty_whitelist = set()


class KnownFieldsMixin:
    """
    Django REST Framework `Serializer` class mixin that provides a
    `run_validation` method which requires that no unknown fields are present
    in serialized data.
    """
    @classmethod
    def get_unknown_fields_whitelist(cls):
        try:
            return cls._unknown_fields_whitelist
        except AttributeError:
            pass

        Meta = getattr(cls, 'Meta', None)
        try:
            raw_whitelist = Meta.unknown_fields_whitelist
        except AttributeError:
            whitelist = empty_whitelist
        else:
            whitelist = set(raw_whitelist)

        cls._unknown_fields_whitelist = whitelist
        return whitelist

    def run_validation(self, data=empty):
        if data is not empty:
            unknown_fields = (
                set(data.keys()) -
                set(self.fields.keys()) -
                self.get_unknown_fields_whitelist()
            )

            if unknown_fields:
                errors = ['Unknown fields: {}'.format(', '.join(unknown_fields))]

                raise serializers.ValidationError({
                    api_settings.NON_FIELD_ERRORS_KEY: errors,
                })

        return super().run_validation(data)


class KnownFieldsSerializer(KnownFieldsMixin, serializers.Serializer):
    pass


class KnownFieldsModelSerializer(KnownFieldsMixin, serializers.ModelSerializer):
    pass