custom decorator for class viewsets

Question

I have a view set like this

class NeProjectsViewSet(viewsets.ViewSet):

   def list(self, request,org_unique_id):
       ''' something '''

   def create(self, request,org_unique_id):
       ''' something '''

   def retrieve(self):
       ''' something '''

   def update(self, request, pk):
       ''' something '''

   def partial_update(self, request):
       ''' something '''

   def destroy(self, request):
       ''' something '''

and i've a method like this

def check_session(self,request):
    current_datetime = datetime.now()
    if ('last_login' in request.session):
        last = (current_datetime - datetime.strptime(request.session['last_login'], "%Y-%m-%d %H:%M:%S.%f")).seconds
        if last > base.SESSION_IDLE_TIMEOUT:
            del request.session['token']
            raise ValueError('Session Expired')
    else:
        request.session['last_login'] = str(current_datetime)
    return (request.session['token'] == request.META['HTTP_AUTHORIZATION'])

to validate session for every request, for that i need to call this method before every method in the viewset. I read somewhere writing custom decorator is better way, so how to implement custom decorator for my view set to check session for request

Answer 1

Assuming you are using DRF.

I think you are going in wrong direction. If this is part of your permission layer you should just add custom permission class to your viewset

http://www.django-rest-framework.org/api-guide/permissions/

from rest_framework import permissions

class ValidateSession(permissions.BasePermission):
    """
    Validate session expiration
    """

    def has_permission(self, request, view):
        current_datetime = datetime.now()
        if ('last_login' in request.session):
            last = (current_datetime - datetime.strptime(request.session['last_login'], "%Y-%m-%d %H:%M:%S.%f")).seconds
            if last > base.SESSION_IDLE_TIMEOUT:
                del request.session['token']
                return False
        else:
            request.session['last_login'] = str(current_datetime)
        return (request.session['token'] == request.META['HTTP_AUTHORIZATION'])

And then add it like this

class NeProjectsViewSet(viewsets.ViewSet):
    permission_classes = (ValidateSession,)
    ...

Assuming you're using plain django

from django.contrib.auth.mixins import AccessMixin

class ValidateSessionMixin(AccessMixin):
    """
    Validate session
    """
    def has_permission(self):
        current_datetime = datetime.now()
        request = self.request
        if ('last_login' in request.session):
            last = (current_datetime - datetime.strptime(request.session['last_login'], "%Y-%m-%d %H:%M:%S.%f")).seconds
            if last > base.SESSION_IDLE_TIMEOUT:
                del request.session['token']
                return True
        else:
            request.session['last_login'] = str(current_datetime)
        return (request.session['token'] == request.META['HTTP_AUTHORIZATION'])

    def dispatch(self, request, *args, **kwargs):
        if not self.has_permission():
            return self.handle_no_permission()
        return super(ValidateSessionMixin, self).dispatch(request, *args, **kwargs)

And apply this mixin like this

class NeProjectsViewSet(ValidateSessionMixin, viewsets.ViewSet):
    ...