Does this protect me against page reload and the back button?
<p>Further to my <a href="http://stackoverflow.com/questions/4142809/seeking-simple-post-redirect-get-code-example">previous question</a>, here's what I decided to implement; it may not be pure P-R-G, but it seems ok. Care to comment?</p>

<p>The form.php has an action; let's call it validate.php.</p>

<p>validate.php is never seen by the user; if validates all <code>$_GET</code> and, if valid writes it to database and generates the HTML of a confirmation page / if not valid, it generates the HTML of an error page explaining what is wrong. </p>

<p>Whichever HTML is generated get stored in a <code>$_SESSION</code> variable and then validate.php does a <code>header('Location: &lt;as appropriate&gt;);</code></p>

<p>Finally a page called <code>submitted.php</code> of <code>invalid_input.php</code> (in case the user reads the URL) consists only of <code>echo $_SESSION['form_html'];</code></p>

<p>That seems to me like is proff against both page reload and back button problems. </p>

<p>Or did I goof by trying to reinvent the wheel?</p>
