import json
from django.db import Model


class MyModel(Model):
    ...
    def to_json(self):
        ...

def validate_<field>(self, field):
  if ...:
    raise serializers.ValidationError
  return field

def validate(self, items):
  return items

def perform_create(self, serializer):
    serializer.save(
        owner=self.request.user
    )

class ModelViewSet(
        mixins.CreateModelMixin,
        mixins.RetrieveModelMixin,
        mixins.UpdateModelMixin,
        mixins.DestroyModelMixin,
        mixins.ListModelMixin,
        GenericViewSet
):

class SnippetsViewSet(
        mixins.CreateModelMixin,
        mixins.RetrieveModelMixin,
        mixins.ListModelMixin
):

class SnippetsViewSet(ModelViewSet):
    ...
    http_method_names = ["get", "post"]

class CreateModelMixin:
  """
  Create a model instance.
  """
  def create(self, request, *a, **k):
     serializer = self.get_serializer(
       data=request.data)
     serializer.is_valid(
       raise_exception=True)
     self.perform_create(serializer)
     # ...

  def perform_create(self, serializer):
    serializer.save()

def get_queryset(self):
  langs = (
    self.request.query_params
    .getlist('langs')
  )
  qs = Recipe.objects
  if tags:
    qs = qs.filter(language__in=langs)
  # if self.request.query_params.get(
  #     'is_favorited'):
  #   qs = qs.filter(is_favorited=True)
  return qs