How to Pass a Class Field to a Decorator on a Class Method as an Argument?

Decorating Class Methods with Self Arguments

To pass a class field to a decorator on a class method as an argument, it's necessary to access the field at runtime rather than at class definition time. Here's how:

1. Intercept the Method Arguments

The decorator can intercept the method arguments using a wrapper function. The first argument to the wrapper will be the instance (self).

<code class="python">def check_authorization(f):
    def wrapper(*args):
        print(args[0].url)
        return f(*args)
    return wrapper</code>

2. Use Getattr to Access Field Dynamically

Alternatively, the field name can be passed to the decorator as a string and accessed using getattr:

<code class="python">def check_authorization(attribute):
    def _check_authorization(f):
        def wrapper(self, *args):
            print(getattr(self, attribute))
            return f(self, *args)
        return wrapper
    return _check_authorization</code>

With this method, the decorator can be called with the desired attribute name as an argument.

Example

<code class="python">@check_authorization("url")
def get(self):
    do_work()</code>

In this example, the decorator will access the url attribute of the instance at runtime.

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