Preventing form resubmission

Question

Page one contains an HTML form. Page two - the code that handles the submitted data.

The form in page one gets submitted. The browser gets redirected to page two. P

Answer 1

I really like @Angelin's answer. But if you're dealing with some legacy code where this is not practical, this technique might work for you.

At the top of the file

// Protect against resubmits
if (empty($_POST))  {
   $_POST['last_pos_sub'] = time();
} else {
     if (isset($_POST['last_pos_sub'])){
        if ($_POST['last_pos_sub'] == $_SESSION['curr_pos_sub']) {
           redirect back to the file so POST data is not preserved
        }
        $_SESSION['curr_pos_sub'] = $_POST['last_pos_sub'];
     }
}

Then at the end of the form, stick in last_pos_sub as follows:

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