proper PRG form handling

[jodunno]

Hello everyone, I've recently asked a question about forms and Requinix mentioned PRG method of processing forms. The PRG idea solves my refresh and back button document expired problems but i notice something new: when i refresh a page or use the browser back button - then return to the PRG process - repeat a refresh or back button action - i notice that i can traverse the cache history as many times as my prg approach redirects me. I feel like i am not implementing this PRG method correctly, or is this correct?

Here is the form process if it helps solve the problem:

i have a login form which contains a CSRF token. when i submit the form i specify an action as /prg/ which submits the data to index.php in the prg folder. After processing the data, prg index.php redirects to the root (because you are logged in). One problem is that i have a logo on the login page that allows you to return to the root (localhost index page). When the form is not submitted or it contaiuns incorrect login data or the logo is clicked to return to homepage, then the history seems to repeat itself. I've read that people recommend to use a header 303 See Other but the result is the same. Basiclly, if i am implementing a prg correctly, then the question becomes how can i instruct a browser to ignore the redirect as if the cache contains only the index page?

i cannot find prg examples that involve a csrf token and other links on the protected page (prg/index.php protected because you need a form submission with a csrf token and it only processes data then redirects.) I don't see this happening in professional sites like Google or Microsoft etc. what am i doing wrong?

[mac_gyver]

the Redirect part of PRG is to the exact same URL that the post method form submitted to. if after successfully processing the post method form data, you are redirecting to a different URL, that's not what the PRG pattern is.