Re: How to avoid "Page expired" going back to post-CGI form confirmation?

The refresh warning is intentional browser behavior to avoid users to resubmit (but then you're right in that they might still hit refresh and resubmit anyway).

A workaround is to replace the usual submit with an XMLHttpRequest call that performs a similar post action underneath the surface. In this case the original page remains available and the user can press Back/Forward buttons without accidental re-post and associated warnings.

To accomplish this XMLHttpRequest call within Perl you can use module CGI::Ajax
Try the code below as an example:

#!/usr/bin/perl -w

use strict;
use CGI::Ajax;
use CGI qw(:all);

my $cgi = new CGI;
my $pjx = new CGI::Ajax('submitted_formdata' => \&process_formdata);
print $pjx->build_html($cgi,\&show_some_html);


sub show_some_html {
  return <<'END_HTML';
<html>
<head><title>Form without post warnings</title></head>
<body>
Please fill in the form:
<form method="POST" >
Your name?
<input type="text" name="surname" id="surname">
<input type="button" onClick=
 "submitted_formdata( ['surname'],['response1'],'POST');"
   value="Submit">
</form>
<div id="response1" name="response1"></div>

<p>
To view some other page goto <a href="http://www.perlmonks.org">Perlmo
+nks</a>
<br>Then try back button
</body>
</html>
END_HTML
}

sub process_formdata {
    my $surname = shift;
    return "Thank you for submitting your surname as '$surname'";
}
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