[Fixed]-Decorators run before function it is decorating is called?

python decorators are functions applied to a function to transform it:

@my_decorator
def function (): ...

is like doing this:

def function():...
function = my_decorator(function)

What you want to do is:

def get_booking(f=None):
    def wrapper(request, **kwargs):
        print "Calling get_booking Decorator"
        booking = _get_booking_from_session(request)
        if booking == None:
            # we don't have a booking in our session.
            return HttpRedirect('/')
        else:
            return f(request=request, booking=booking, **kwargs)
    return wrapper

Since you are starting with decorators, I think reading these will be helpful, so that you know the pitfalls and workarounds beforehand.

Here are two links to earlier discussions on decorators.

Python decorator makes function forget that it belongs to a class
What does functools.wraps do?

Moreover the second link mentions ‘functools’ a module for higher-order functions, that act on or return other functions. Use of functools.wraps is advised since it preserves the doc string of the original function(decorated one).

Another issue was wrong method signatures while generating automatic docs for my project.
but there is a workaround:
Preserving signatures of decorated functions

Hope this helps.

A decorator is called as soon as the decorated function is defined. It is equivalent to writing something like this:

def __do_stuff(...):
    ...

do_stuff = get_booking(__do_stuff)