Document when process_response and process_exception middleware is invoked

[TP]

It would be helpful if the django docs better covered the exact semantics of when middleware handlers are invoked. For example, if there's an exception will my custom middleware's process_exception hander be called? How about my process_response handler? This caused some subtle bugs on our website and I thought the docs could go into this more to help other people.

It turns out that django runs exception handlers specified in middleware until one of them returns a response or until django has executed every exception handler. This means your custom handler may or may not be invoked. Second, if some exception handler returns a HttpResponse then the response handlers will be invoked. So your custom process_response may or may not be called after an exception occurs.

[Jacob]

There's a graphic in ch 3 of the django book that explains this; we should adapt it into the middleware docs for clarity.

[Jeff Anderson]

I'm willing to write a patch for this. Is it appropriate to take the graphic from the Django book verbatim and include it here?

[Brantley]

Ah, sorry hadn't updated and just did this. Go ahead programmerq, if you want to take from the book.

[Jacob]

This has been fixed for a bit; not exactly sure when it got checked in.

[Jacob]

Milestone 1.1 deleted