Question

When a user of my GAE app clicks the back button, I need to prevent them from seeing a cached version of the page – that is, I need the python get or post code for that url to be run.

Answer 1

The answer provided by chachan would not work across all browsers. A more complete answer could be found in this answer. Basically, you would need to set all these headers:

<meta http-equiv="cache-control" content="no-cache, no-store, must-revalidate">
<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="0">

to tell the browser to always fetch the page from the server.