CODEWITHSUNDEEP
pythondjango
Chris
Chris

Reputation: 703

What does test_func and view_func do in Python / Django?

I'm trying to break-down the following code in Django to figure out what it's doing and edit it if necessary, but I can't quite figure out what a few of these functions are doing or where they're coming from.

Are test_func and view_func Django specific or are these built-in python functions?

Conclusion: I'm not sure how/why I overlooked the fact that these were simply being defined as arguments to the functions. I need to start paying better attention to details.

Here's the Django function I'm trying to break down / figure out:

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):
            print test_func
            if test_func(request.user):
                return view_func(request, *args, **kwargs)
            path = request.build_absolute_uri()
            # 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.urlparse(login_url or
                                                        settings.LOGIN_URL)[:2]
            current_scheme, current_netloc = urlparse.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, login_url, redirect_field_name)
        return _wrapped_view
    return decorator

Upvotes: 7

Views: 6968

Answers (4)

Abpostman1
Abpostman1

Reputation: 192

Illustrating with real-life case can help to understand better.

Let's take the example of an article written by a certain author. We don't want any author to be able to modify it. Only its author will be able to do so:

class PostUpdateView(LoginRequiredMixin, UserPassesTestMixin, UpdateView):
    model = Post
    fields = ['title', 'content']

    def form_valid(self, form):
        # author = current user
        form.instance.author = self.request.user
        return super().form_valid(form)

    def test_func(self):
        post = self.get_object()
        if self.request.user == post.author:
            return True
        return False

Upvotes: 0

snakecharmerb
snakecharmerb

Reputation: 55600

Class-based views that inherit from UserPassesTestMixin define a test_func method that performs the same function as the decorator parameter described in the existing answers [1, 2], that is it determines whether the user may view the page.

class MyView(UserPassesTestMixin, View):
    def test_func(self):
        return self.request.user.some_atttribute == acceptable_Value

Upvotes: 0

agf
agf

Reputation: 176760

view_func is a Django view. test_func is a function "that checks that the user passes the given test".

So, you write a function that asks for something from the user, and returns True if they pass. Then you pass that function to user_passes_test and it creates a decorator you can use to first test a user before they get to see your view, like so:

@user_passes_test
def test_intelligence(user):
    if is_intelligent:
        return True
    else:
        return False

@test_intelligence
def my_view(request):
    #this is the view you only want intelligent people to see
    pass

Decorators are mentioned under Function Definitions in the docs. wraps is a decorator that preserves the signature of the function being wrapped (name, args, etc) through the decoration process. It's located in functools.

Upvotes: 5

Ismail Badawi
Ismail Badawi

Reputation: 37177

test_func and view_func are functions passed in as arguments -- that is, the names are just arbitrary variables names. user_passes_test is a decorator which is applied to a view (which becomes the variable view_func) -- it's passed a function as argument (test_func) which takes a User and returns True or False.

Upvotes: 2

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