id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
5797	decorator_from_middleware can cause middleware hooks to run out of correct order.	Jeremy Dunck		"cache_page, gzip_page, and conditional_page all use decorator_from_middleware.

decorator_from_middleware wraps the view function to simulate middleware being run on a per-view basis.

Here's the interesting bit:
{{{
        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
}}}

The problem is that middleware's order is important.  Suppose two middleware decorators, A and B, are applied to the same view.

The normal flow of middleware processing would be: A.process_request, B.process_request, A.process_view, B.process_view, view, B.process_response, A.process_response.

The flow of the *decorated execution* is this:  A.process_request, A.process_view, B.process_request, B.process_view, view, B.process_response, A.process_response.

This is not yet a real-world issue as far as I know, but seems to be a lurking problem.  I think the only reason it hasn't surfaced is that view decorators are fairly uncommon.  I don't see a simple way to fix this."	Bug	new	HTTP handling	dev	Normal		cache middleware decorator gzip conditional http	hirokiky@… Herbert Fortes	Accepted	1	0	0	1	0	0