This is a good reason why you shouldn't use redirects for forms which have not been filled out correctly. The page which generates the HTML form should be the same page which submits it.
That way you can put the incorrect information back into the form and provide them with user friendly messages. Take a look at this:
<?php ob_start(); ?>
<html>
<head>
<title>Form Demo</title>
</head>
<?php
if (isset($_POST['submit'], $_POST['name'], $_POST['desc'])) {
/* this flag is used to determine whether or not we re display the form */
$data['valid'] = true;
/* prepare input for database */
if (! get_magic_quotes_gpc()) {
$data['name']['data'] = addslashes($_POST['name']);
$data['desc']['data'] = addslashes($_POST['desc']);
} else {
$data['name']['data'] = $_POST['name'];
$data['desc']['data'] = $_POST['desc'];
}
if (stripslashes($data['name']['data']) == '') { /* check name is supplied */
$data['name']['err'] = 'You cannot leave this field blank.';
$data['valid'] = false;
} else if (strlen(stripslashes($data['name']['data'])) > 20) { /* check name is not too long */
$data['name']['err'] = 'Your name cannot be longer than 20 characters.';
$data['valid'] = false;
}
if (strlen(stripslashes($data['desc']['data'])) > 500) { /* check description is not too long */
$data['desc']['err'] = 'Your name cannot be longer than 500 characters.';
$data['valid'] = false;
}
if ($data['valid']) { /* if form data was all OK do database stuff and redirect */
/* do database stuff here */
echo('<h3>you have been successfully processed.</h3><p>You will be redirected shortly.</p>');
header('Refresh: 3; url=http://www.vbforums.com/');
} else {
/* re display the form */
display_form($data);
}
} else {
/* nothing submitted - display empty form */
display_form();
}
function display_form($data = null)
{
?>
<form action="<?php echo($_SERVER['PHP_SELF']); ?>" method="post">
<p>
<?php if (!is_null($data) && isset($data['name']['err'])): ?>
<p style="font-weight: bold; color: red;"><?php echo($data['name']['err']) ?></p>
<?php endif; ?>
Enter Your Name: <input type="text"
value="<?php if (! is_null($data)) echo_html_strip($data['name']['data']); ?>"
name="name" /><br />
<?php if (!is_null($data) && isset($data['desc']['err'])): ?>
<p style="font-weight: bold; color: red;"><?php echo(htmlspecialchars($data['desc']['err'])) ?></p >
<?php endif; ?>
Enter a description: <input type="text"
value="<?php if (! is_null($data)) echo_html_strip($data['desc']['data']); ?>"
name="desc" />
</p>
<p><input type="submit" name="submit" /></p>
<?php
}
?>
</body>
</html>
<?php
function echo_html_strip($text)
{
echo(htmlspecialchars(stripslashes($text)));
}
?>
You can see how it works here: http://adam.codedv.com/form.php
In my opinion its a lot cleaner doing it this way. It centralises everthing. ;)