app/django/utils/decorators.py
author Todd Larsen <tlarsen@google.com>
Fri, 03 Oct 2008 01:32:34 +0000
changeset 263 9b39d93b677f
parent 54 03e267d67478
permissions -rw-r--r--
Make findNearestUsers() code in soc/logic/site/id_user.py more generic and move it to soc/logic/model.py. Orginal findNearest...() functions in id_user.py are now convenience wrappers. Add typed-query string construction functions to model.py. Move getFulLClassName() from key_name.py model.py, since it has more to do with Model types than key names. Swap 'offset' and 'limit' and make 'limit' arguments non-optional. Also, stop adding 1 inside the ...ForLimitAndOffset() functions and make the callers do it (since it was being added for a very UI-specific reason of whether or not to display a "Next>" link). Patch by: Todd Larsen Review by: Pawel Solyga Review URL: http://codereviews.googleopensourceprograms.com/1401

"Functions that help with dynamically creating decorators for views."

import types
try:
    from functools import wraps
except ImportError:
    from django.utils.functional import wraps  # Python 2.3, 2.4 fallback.

def decorator_from_middleware(middleware_class):
    """
    Given a middleware class (not an instance), returns a view decorator. This
    lets you use middleware functionality on a per-view basis.
    """
    def _decorator_from_middleware(*args, **kwargs):
        # For historical reasons, these "decorators" are also called as
        # dec(func, *args) instead of dec(*args)(func). We handle both forms
        # for backwards compatibility.
        has_func = True
        try:
            view_func = kwargs.pop('view_func')
        except KeyError:
            if len(args):
                view_func, args = args[0], args[1:]
            else:
                has_func = False
        if not (has_func and isinstance(view_func, types.FunctionType)):
            # We are being called as a decorator.
            if has_func:
                args = (view_func,) + args
            middleware = middleware_class(*args, **kwargs)

            def decorator_func(fn):
                return _decorator_from_middleware(fn, *args, **kwargs)
            return decorator_func

        middleware = middleware_class(*args, **kwargs)

        def _wrapped_view(request, *args, **kwargs):
            if hasattr(middleware, 'process_request'):
                result = middleware.process_request(request)
                if result is not None:
                    return result
            if hasattr(middleware, 'process_view'):
                result = middleware.process_view(request, view_func, args, kwargs)
                if result is not None:
                    return result
            try:
                response = view_func(request, *args, **kwargs)
            except Exception, e:
                if hasattr(middleware, 'process_exception'):
                    result = middleware.process_exception(request, e)
                    if result is not None:
                        return result
                raise
            if hasattr(middleware, 'process_response'):
                result = middleware.process_response(request, response)
                if result is not None:
                    return result
            return response
        return wraps(view_func)(_wrapped_view)
    return _decorator_from_middleware