ActionSerializerMixin for the Django Rest Framework. Allows usage of multiple serializers for a single ViewSet

mixins.py

from typing import Union, Dict
from rest_framework.viewsets import GenericViewSet
from rest_framework.serializers import BaseSerializer


class ActionSerializersMixin(object):
    """
    Allows the usage of different serializer classes depending on the action.
    When your `ViewSet` class is using this mixin, it should provide a `serializer_classes` attribute instead
    of a `serializer_class` attribute. This attribute must be dict, which provides for every action name the
    desired serializer class (type `Dict[str, BaseSerializer]`)

    Thanks to https://stackoverflow.com/a/30670569/458274
    """
    serializer_classes: Dict[str, BaseSerializer] = None

    # Best way to do type hinting with mixins?
    # https://stackoverflow.com/a/52313062/458274
    def get_serializer_class(self: Union[GenericViewSet, 'ActionSerializersMixin']) -> BaseSerializer:
        assert self.serializer_classes is not None, (
            f"'{self.__class__.__name__}' should include a `serializer_classes` attribute, "
            f"providing a SerializerClass for each action"
        )
        assert self.action in self.serializer_classes, (
            f"'{self.__class__.__name__}' should provide a serializer class for "
            f"the action '{self.action}'"
        )
        return self.serializer_classes[self.action]