Re: Decorator function argument woes

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>> 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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