Problem on reloading a page

[rolwong]

I have this line in my page "compose.php".

if (isset($POST["mailTo"])) {
$mailTo = $POST["mailTo"];
}
...
..
<form action="compose.php" method="post">
print "<input type='text' name='mailTo' value='".$mailTo."'>";

There is a submit button, when i click it, it will reload the page. And it will keep what the user has written in the text field. What my problem right now is: When I press F5 to reload the page, $_POST["mailTo"] is still there. I want to get rid of the POST's value when I press F5 button, and the text field will only display the POST's value ONLY when the value is POST by clicking the submit button. How could I handle this 2 situation?

[rehfeld]

you cant. posting data to a server is a way to request a page. to refresh the page, requires resending the data.

you could however, not accept a second submission from them. for examples use sessions to keep track of whether they submitted the form already or not.

or, upon accpting the submission, redirect them to another page so refreshing the page at that point wouldnt submit the form anymore.

[rolwong]

Thanks for the reply. As my button functions like adding attachment (add attachment) of a web mail system, it needs to allow users to submit more than once and has to direct to the same page again before users click the "send" button. Base on this, any methods to distinguish if the user is submitting or they are refreshing by F5?

[rehfeld]

sure. we can use sessions to keep track of which submission were dealing with.

<?php

session_start();


// initialize the variable
if (!isset($_SESSION['last_submission_id'])) {
    $_SESSION['last_submission_id'] = '';
}


// if they submitted the form
if (isset($_POST['submission_id'])) {
    // check if this submission id is the same as the last id we accepted data from
    if ($_POST['submission_id'] == $_SESSION['last_submission_id']) {
        echo '<h1>dont refresh the page please</h1>';
        // do not accept this form
    } else {
        // accept the form
        // since we accepted it, record the id of this form submission
        $_SESSION['last_submission_id'] = $_POST['submission_id'];
    }
}

// make a new one every time.
$next_submission_id = uniqid();



?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<input type="hidden" name="submission_id" value="<?php echo $next_submission_id; ?>">
<input type="submit">
</form>

keep in mind, this wont only stop from re-submitting the last form they submitted again. if they make, say 5 valid submission, then hit the back button 3 times, then hit refresh, this WILL allow it.

to get around that, you would have to use an array in the session to store all submission_id's.