[Django]-Django: a class based view with mixins and dispatch method

For the example you gave, I would use UserPassesTestMixin from django-braces.

class GenerateReportView(UserPassesTestMixin, FormView):
    def test_func(self, user):
        return user.is_superuser or user.is_manager

If that isn’t suitable for your more complicated logic, then creating a separate mixin sounds like an OK approach, as it encapsulates the complicated logic nicely.

EDIT
As of django 1.9, the UserPassesTestMixin is now included in django: https://docs.djangoproject.com/en/1.11/topics/auth/default/#django.contrib.auth.mixins.UserPassesTestMixin

this is an old post but other people might come across so here is my proposed solution.

When you say

“[…]I want to add some permissions for this view or set some
initial variables, for example[…]”

Instead of setting those initial variables in the dispatch method of your view, you could write a separated method for setting up those variables, and then call that method in your get (and post if needed) method. They are called after dispatch, so setting up your initial variables wont clash with the dispatch in your mixins.
So override the method

def set_initial_variables():
    self.hey = something
    return 

def get(blablabla):
    self.set_initial_variables()
    return super(blabla, self).get(blabla)

This probably is cleaner than copying and pasting the code of your mixin in your view’s dispatch.

It can be done with Django UserPassesTestMixin mixin or @user_passes_test decorator.

Example of UserPassesTestMixin

from django.contrib.auth.mixins import UserPassesTestMixin


class SuperUserOrManagerRequiredMixin(UserPassesTestMixin):
    def test_func(self):
        if self.request.user.is_superuser or self.request.user.is_manager:
            return True

        return False


class MyView(LoginRequiredMixin, SuperUserOrManagerRequiredMixin, View):
    ...

If you override the dispatch, like you’ve noticed, your LoginRequiredMixin would stop working. While you could add a check to see if the user is authenticated, just that check wouldn’t be enough to handle the redirects too.

Just like mentioned in two other answers, I also prefer to use UserPassesTestMixin with a test_func() method containing the logic. The reason I’m writing this answer is to show it can be used

• together with the LoginRequiredMixin
• for more complex cases (with try/excepts for example)

Here’s what I’d do in your case

from django.views.generic.edit import FormView
from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin

class GenerateReportView(LoginRequiredMixin, UserPassesTestMixin, FormView):
    template_name = 'reporting/reporting_form.html'
    form_class = ReportForm

    def test_func(self):
        if not (
            self.request.user.is_superuser or
            self.request.user.is_manager
        ):
            return False
        try:
            # some logic
            return True
        except:
            return False

Notice the usage of LoginRequiredMixin before UserPassesTestMixin. The order is relevant. It means that it’ll check if the user is authenticated first, before checking the test_func(). If the user is not authenticated, then will be redirected to the login page.

Also, I like how you use the if not (...), which was adapted to

if not (...):
    return False

In addition to that, since you’re looking for some more logic, you can do that with a try/except block (which could even call another function(s))

try:
    # some logic
    return True
except:
    return False

return True is to say that the user has then permissions to access the view, whereas return False will give to the user a 403 status code.