class StaffRequiredMixin(object):
    """
    View mixin which requires that the authenticated user is a staff member
    (i.e. `is_staff` is True).
    """

    @method_decorator(login_required)
    def dispatch(self, request, *args, **kwargs):
        if not request.user.is_staff:
            messages.error(
                request,
                'You do not have the permission required to perform the '
                'requested operation.')
            return redirect(settings.LOGIN_URL)
        return super(StaffRequiredMixin, self).dispatch(request,
            *args, **kwargs)