How to create a decorator for checking groups in Django

Sometimes, in the Django framework, it needs to wrap a view function into a decorator, that checks to contain if a user is in certain groups.

There are several requirements for our decorator:

1. Ability to checking multiple groups at the same time
2. Ability to changing a list of the groups in decorator arguments
3. The decorator can contain some custom behavior. For example, only admins might know about existing some pages, other users getting 404 error.

Let`s create a module for decorators, name it “decorators.py” and write a simple decorator. That decorator checks to contain if a user in the “admin” group. If the check was not passed, then we return 404.

We can use this decorator like this in views.py:

@check_user_able_to_see_page
def hidden_page(request):
    ....

There is a problem. If we want to add permission to the page for another group, then we need to change our decorator or create a new one. If we have several pages and each page needs to have a custom group check, then we need to create multiple decorators.

A decorator takes just one argument: the function to be decorated. There is no way to pass on other arguments. Let`s create a decorator factory. A decorator factory is a function that returns a decorator.

Thus, you can use it like:

@check_user_able_to_see_page("admin")
def hidden_page(request):
    ....

or

@check_user_able_to_see_page("manager")
def hidden_page(request):
    ....

or even

@check_user_able_to_see_page("admin", "manager")
def hidden_page(request):
    ....

It is a good variant, but let`s add some beautiful things. Create a module with an enumeration of groups:

# constants.py
from enum import Enum
class Group(Enum):
    admin = "Administrator"
    manager = "Manager"

Rewrite the decorator:

Then you can use it like:

from .constants import Group
@check_user_able_to_see_page(Group.admin)
def hidden_page(request):
    ...