Using $_POST information only once

Question

I have some information which gets passed from a form and needs to be used once and only once. I can collect it nicely from $_POST but I'm not sure which is the "best" way to ensure that I can only use it once, i.e. I want to avoid the user pressing F5 repeatedly and accessing the function more than once.

My initial thought was to set a session variable and time the function out for a set period of time. The problem with that is thay could have access to the function again after the set period has elapsed.

Better ideas welcomed!

Answer 1

A redirect to another page would be sufficient to break most browser repost-on-refresh behaviour. Setting a cookie on form submit (or a session variable, as you suggest) would also work quite nicely. You could have the form submission page unset the session variable again, such that only a fresh access to the form would permit re-submitting the form.

Answer 2

This one's VERY easy to implement.

All you need to do is this:

have your form submit to a different page, which will only handle the post information, and not display ANYTHING

Then, send a LOCATION header to redirect the browser to a new page (which will be retreived by GET) This will break the browser's repost-on-refresh behaviour