pxUx pxUx - 6 months ago 22
Python Question

How to use the user_passes_test decorator in class based views?

I am trying to check certain conditions before the user is allowed to see a particular user settings page. I am trying to achieve this using the user_passes_test decorator. The function sits in a class based view as follows. I am using method decorator to decorate the get_initial function in the view.

class UserSettingsView(LoginRequiredMixin, FormView):
success_url = '.'
template_name = 'accts/usersettings.html'

def get_form_class(self):
if self.request.user.profile.is_student:
return form1
if self.request.user.profile.is_teacher:
return form2
if self.request.user.profile.is_parent:
return form3

@method_decorator(user_passes_test(test_settings, login_url='/accounts/usertype/'))
def get_initial(self):
if self.request.user.is_authenticated():
user_obj = get_user_model().objects.get(email=self.request.user.email)
if user_obj.profile.is_student:
return { ..........
...... ....


Below is the test_settings function:

def test_settings(user):
print "I am in test settings"
if not (user.profile.is_student or user.profile.is_parent or user.profile.is_teacher):
return False
else:
return True


I am getting the below error with the decorator.

File "../django/core/handlers/base.py", line 111, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "../django/views/generic/base.py", line 69, in view
return self.dispatch(request, *args, **kwargs)
File "../braces/views.py", line 107, in dispatch
request, *args, **kwargs)
File "../django/views/generic/base.py", line 87, in dispatch
return handler(request, *args, **kwargs)
File "../django/views/generic/edit.py", line 162, in get
form = self.get_form(form_class)
File "../django/views/generic/edit.py", line 45, in get_form
return form_class(**self.get_form_kwargs())
File "../django/views/generic/edit.py", line 52, in get_form_kwargs
'initial': self.get_initial(),
File "../django/utils/decorators.py", line 29, in _wrapper
return bound_func(*args, **kwargs)
TypeError: _wrapped_view() takes at least 1 argument (0 given)


I am not sure how to resolve this error. Am I applying the decorator on the wrong function? Any leads will be helpful.

Answer

Django 1.9 has authentication mixins for class based views. You can use the UserPassesTest mixin as follows.

from django.contrib.auth.mixins import LoginRequiredMixin, UserPassesTestMixin

class UserSettingsView(LoginRequiredMixin, UserPassesTestMixin, View):
    def test_func(self):
        return test_settings(self.request.user)

    def get_login_url(self):
        if not self.request.user.is_authenticated():
            return super(UserSettingsView, self).get_login_url()
        else:
            return '/accounts/usertype/'

Note that in this case you have to override get_login_url, because you want to redirect to a different url depending on whether the user is not logged in, or is logged in but fails the test.

For Django 1.8 and earlier, you should decorate the dispatch method, not get_initial.

@method_decorator(user_passes_test(test_settings, login_url='/accounts/usertype/')) 
def dispatch(self, *args, **kwargs):
    return super(UserSettingsView,  self).dispatch(*args, **kwargs)
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