access function arguments from function decorator

Question

If I have a function that looks like:

@app.route('/categories/id/<int:id>/edit')
@login_required
def edit_category(id):
   #some code...

And the login_required decorator looks like this

def login_required(f):
   @wraps(f)
   def wrapper(*args, **kwargs):
       print id #given to edit_category by app.route decorator
       return f(*args, **kwargs)
   return wrapper

How do I access the id variable that is given to edit_category as an argument by the app.route decorator, from the login_required decorator?

Answer 1

The positional arguments to the wrapper function come in the args (first argument - *args ) , and the keyword arguments for the method come in kwargs (second argument - **kwargs ).

args is a tuple , where the first element refers to the first positional argument, second element is the second positional argument.

kwargs is a dictionary , where the key is the keyword (for the argument) and the value is the value passed in for that keyword.

Example -

>>> def decor(func):
...     def wrapper(*args, **kwargs):
...             print('args - ',args)
...             print('kwargs - ',kwargs)
...             return func(*args, **kwargs)
...     return wrapper
...
>>> @decor
... def a(*a, **b):
...     print("In a")
...     print(a)
...     print(b)
...
>>> a(1,2,x=10,y=20)
args -  (1, 2)
kwargs -  {'y': 20, 'x': 10}
In a
(1, 2)
{'y': 20, 'x': 10}

You can test whether app.route is sending id as positional argument or keyword argument by printing both args and kwargs and take the correct value. I think it may be coming in as positional argument, if so, it would be the first element of args .