How do I write a decorator for my Django/Python vi

问题:

Here's my view. Basically, it returns different Responses based on whether it's logged in or not.

@check_login()
def home(request):
    if is_logged_in(request): 
        return x
    else:
        return y

Here's my decorator code. I just want to check if the request has headers, and if so, log him in.

#decorator to log the user in if there are headers
def check_login():
    def check_dec(func):
        if request.META['username'] == "blah":
            login(request, user)

    return check_dec

The problem is..I don't know how to write a proper decorator in this case!!! What are the arguments? What are the functions? How?

回答1:

Use only @check_login instead of check_login() - otherwise your decorator has to return a decorate as you are doing home = check_login()(home)

Here's an example decorator:

def check_login(method):
    @functools.wraps(method)
    def wrapper(request, *args, **kwargs):
        if request.META['username'] == "blah"
            login(request, user) # where does user come from?!
        return method(request, *args, **kwargs)
    return wrapper

This decorator will call execute your login function if the username field is set to "blah" and then call the original method.

回答2:

A plain decorator is simply a function that takes a function or class and returns something else (usually the same type, but this is not required). A parametrized decorator is a function that returns a decorator.

So, with that in mind we create a closure and return it:

def check_login(func):
  def inner(request, *args, **kwargs):
    if request.META['username'] == 'blah':
      login(request, user) # I have no idea where user comes from
    func(request, *args, **kwargs)
  return inner

回答3:

Here is a decorator I wrote to check if the user is in a certain group. It shows a bit more.

https://github.com/mzupan/django-decorators/blob/master/auth.py

You use it like

@group_required(["group1", "group2"])
def show_index(request):
    view_code_here

The user can be in either group1 or group2 if they are not they get a 404 page