Django DRF get request query param in custom decorator applied on a function in viewsets.ViewSet

Question

In django rest framework when create a custom viewsets.ViewSet can we apply a custom decorator on a specific function in that ViewSet?

class UserViewSet(viewsets.ViewSet):
    """
    Example empty viewset demonstrating the standard
    actions that will be handled by a router class.

    If you're using format suffixes, make sure to also include
    the `format=None` keyword argument for each action.
    """

    @permission_classes([IsAuthenticated])
    @custom_decorator_1()
    def list(self, request):
        pass

    @custom_decorator_2()
    def create(self, request):
        pass

    @custom_decorator_3()
    def retrieve(self, request, pk=None):
        pass

    def update(self, request, pk=None):
        pass

    def partial_update(self, request, pk=None):
        pass

    def destroy(self, request, pk=None):
        pass

If yes then how can we get query parameters inside that custom decorator applied on a ViewSet? Or is there any alternate solution to achieve this where I can apply multiple decorators on a ViewSet action?

Right now I am trying to do it in this way:

def custom_decorator():
    """
    Decorator for views that checks that the user passes the given test,
    redirecting to the log-in page if necessary. The test should be a callable
    that takes the user object and returns True if the user passes.
    """

    def decorator(view_func):
        @wraps(view_func)
        def wrapper(request, *args, **kwargs):

            role = request.query_params['role']
            
            return view_func(request, *args, **kwargs)

        return wrapper

    return decorator

Error received:

AttributeError: 'UserViewSet' object has no attribute 'query_params'

Answer 1

Django provides a simple way to use decorators on class based views (this works for DRF as well):

from django.utils.decorators import method_decorator

@method_decorator(login_required) #replace login_required with your own decorator
    def list(self, request):
        pass

More info: https://docs.djangoproject.com/en/3.1/topics/class-based-views/intro/#decorating-the-class

But in your case, I would rather go for DRF own Permissions system ( https://www.django-rest-framework.org/api-guide/permissions/ ):

from rest_framework import permissions

class CustomerAccessPermission(permissions.BasePermission):
    def has_permission(self, request, view):
        return request.query_params['role'] == "admin" #or whatever as long as it is a boolean