Re: Decorator function argument woes

On 30/04/2018 4:30 PM, Stephen J. Butler wrote:
> Yes. I don't see it in the documentation for login_required, but I
> believe it's so that you can do something like this in your urls.py:
>
> urlpatterns = [
>     url(r'^example$', login_required(views.example)),
> ]
>
> That might be an older way of using the decorator? IDK for sure. But
> you can see from the code for login_required that the "test" is always
> a lambda that checks if the user is authenticated; there's no option
> to override it. If the "function" parameter is present then it is used
> as the function be wrapped, not the test being done.

That all makes sense. Thanks again

Cheers

Mike


>
> On Mon, Apr 30, 2018 at 1:24 AM, Mike Dewhirst <miked@dewhirst.com.au
> <mailto:miked@dewhirst.com.au>> wrote:
>
> On 30/04/2018 3:35 PM, Stephen J. Butler wrote:
>
> @login_required doesn't take a test function. You need to use
> @user_passes_test directly.
>
>
> Thank you Stephen.
>
> I thought I'd start another thread to ask about my use case of
> being able to require login or not depending on whether the
> content needed a login or not ... but ... just as I was thinking
> about it I had another look at login_required and thought I'd ask
> one more question.
>
> Its signature is ...
>
> def login_required(function=None,
> redirect_field_name=REDIRECT_FIELD_NAME, login_url=None):
>
> Are you saying that function is the the view function?
>
> M
>
>
> On Mon, Apr 30, 2018 at 12:26 AM, Mike Dewhirst
> <miked@dewhirst.com.au <mailto:miked@dewhirst.com.au>
> <mailto:miked@dewhirst.com.au <mailto:miked@dewhirst.com.au>>>
> wrote:
>
>     I'm pretty sure this is a not-understanding-python problem
> rather
>     than a Django problem but here goes ...
>
>     In a (FBV) view I'm trying to pass a function in to the
>     login_required decorator. My function is called
> 'is_login_needed'
>     and I want the login_required decorator to effectively switch
>     itself off if login is not needed.
>
>     The scenario is on-line training and if the training
> instruction
>     has questions with scores then obviously the user needs to
> login.
>     On the other hand if it is simply a demonstration video or
> plain
>     blah with no questions/answers/scores it should be viewable by
>     anyone whether they are logged in or not.
>
>     My function goes like this and the docstring reveals my
>     understanding ...
>
>     def is_login_needed(user):
>
>         """ the login_required decorator has a user_passes_test()
>     function as
>
>         its first arg. If it returns True, no login is required.
>     user.login_here
>
>         is always set equal to the selected
> course.login_needed. For
>     courses
>
>         needing a login, self.is_authenticated must be True. For
>     courses not
>
>         needing a login, self.is_authenticated may return
> anything but
>     this
>
>         function passed to the login_required decorator must
> return True
>
>         """
>
>         if not user.login_here:
>
>             return True
>
>
>     So   the problem is that manage.py runserver reports an
> attribute
>     error saying the function (presumably mine) does not have an
>     attribute 'user' ... like this ...
>
>       <earlier runserver traceback lines snipped> File
>     "C:\Users\mike\envs\xxct3\train\course\urls.py", line 8,
> in <module>
>
>         from .views import (finished_course_view, course_view,
> index_view,
>
>       File "C:\Users\mike\envs\xxct3\train\course\views.py",
> line 172,
>     in <module>
>
>         def course_view(request, pk=None, slug=None):
>
>       File
>    
> "C:\Users\mike\envs\xxct3\lib\site-packages\django\contrib\auth\decorators.py",
>     line 22, in _wrapped_view
>
>         if test_func(request.user):
>
>     AttributeError: 'function' object has no attribute 'user'
>
>     If that 'function' is my 'is_login_needed' function I'm
> inclined
>     to think it obviously has a 'user' attribute.
>
>     Here is the contrib.auth.decorators.login_required source
>     (preceded by user_passes_test which it calls) from Django 1.11
>
>     My reading of the following  is that my own 'is_login_needed'
>     function passed in via @login_required(is_login_needed,
>     login_url='login') as the first positional argument is
> then passed
>     to the 'user_passes_test' decorator as 'test_func'  ...
>
>
>     def user_passes_test(test_func, login_url=None,
>     redirect_field_name=REDIRECT_FIELD_NAME):
>
>         """
>
>         Decorator for views that checks that the user passes
> the given
>     test,
>
>         redirecting to the log-in page if necessary. The test
> should
>     be a callable
>
>         that takes the user object and returns True if the
> user passes.
>
>         """
>
>         def decorator(view_func):
>
>             @wraps(view_func, assigned=available_attrs(view_func))
>
>             def _wrapped_view(request, *args, **kwargs):
>
>                 if test_func(request.user):
>
>                     return view_func(request, *args, **kwargs)
>
>                 path = request.build_absolute_uri()
>
>                 resolved_login_url = resolve_url(login_url or
>     settings.LOGIN_URL)
>
>                 # If the login url is the same scheme and net
> location
>     then just
>
>                 # use the path as the "next" url.
>
>                 login_scheme, login_netloc =
>     urlparse(resolved_login_url)[:2]
>
>                 current_scheme, current_netloc =
> urlparse(path)[:2]
>
>                 if ((not login_scheme or login_scheme ==
>     current_scheme) and
>
>                         (not login_netloc or login_netloc ==
>     current_netloc)):
>
>                     path = request.get_full_path()
>
>                 from django.contrib.auth.views import
> redirect_to_login
>
>                 return redirect_to_login(
>
>                     path, resolved_login_url, redirect_field_name)
>
>             return _wrapped_view
>
>         return decorator
>
>     def login_required(function=None,
>     redirect_field_name=REDIRECT_FIELD_NAME, login_url=None):
>
>         """
>
>         Decorator for views that checks that the user is
> logged in,
>     redirecting
>
>         to the log-in page if necessary.
>
>         """
>
>         actual_decorator = user_passes_test(
>
>             lambda u: u.is_authenticated,
>
>             login_url=login_url,
>
>             redirect_field_name=redirect_field_name
>
>         )
>
>         if function:
>
>             return actual_decorator(function)
>
>         return actual_decorator
>
>     Could someone please explain where I'm stuffing up. I
> reckon I'm
>     confused about which function the AttributeError is
> complaining.
>
>     Many thanks for any help
>
>     Mike
>
>
>
>
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