custom_model_viewset.py

from rest_framework.viewsets import ModelViewSet
from rest_framework.permissions import IsAuthenticated, AllowAny, IsAdminUser

from blog.models import Post
from blog.serializers import PostSerializer


class CustomModelViewset(viewsets.ModelViewSet):
  """ 
  A class that inherits from ModelViewset and allow to add custom permissions on your views
  without redefine methods
  """
    default_permission = IsAuthenticated
    
    list_permissions = [default_permission]
    create_permissions = [default_permission]
    retrieve_permissions = [default_permission]
    update_permissions = [default_permission]
    destroy_permissions = [default_permission]

    def get_permissions(self):
        permissions = {
          "list": [permission() for permission in self.list_permissions],
          "create": [permission() for permission in self.create_permissions],
          "retrieve": [permission() for permission in self.retrieve_permissions],
          "update": [permission() for permission in self.update_permissions],
          "partial_update": [permission() for permission in self.update_permissions],
          "destroy": [permission() for permission in self.destroy_permissions]
        }
        
        try:
          return permissions[self.action]
        except KeyError:
          return [permission() for permission in self.permission_classes]
      
      
# Usage 

class PostViewset(CustomModelViewset):
  # define serializer and queryset
  serializer_class = PostSerializer
  queryset = Post.objects.all()

  # define permissions for each method of viewset
  list_perimissions = [AllowAny]
  retrieve_permissions= [AllowAny]
  create_permissions = [IsAdminUser]
  delete_permissions = [IsAdminUser]
  update_permissions = [IsAdminUser]