Steady as a rock

One thing I don’t like in django is that there is no from input firld that’s automatically set to the current logged in user (like the auto_now datetimefield). Problem with such a field is that there isn’t always a current user, since you can also manipulate django objects on the command line (which is great!). But given that there sometimes is a user, why not take advantage of that and inspect the request? Problem is that you don’t have access to the current request from everywhere, but it’s somewhere on the call stack. Fortunately, you don’t have to do ASM hacking to access the python callstack, python has a neat little gem called sys._getframe which works real pythonic and doesn’t even run off the stack but raises a ValueError if you try and access a non-existing frame. Don’t forget to del(frame) though, otherwise python (and in the case of mod_python: apache) segfaults.

def get_user():
    i=1
    user = None
    while True:
        try:
            frame = sys._getframe(i)
        except ValueError: # Stack isn't this deep
            break
        if 'request' in frame.f_locals and
           issubclass(type(frame.f_locals['request']) , HttpRequest):
            user = frame.f_locals['request'].user
            del(frame)
            break
        del(frame)
        i += 1
    return user