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One way to stop page resubmission on page refresh is to unset the form data after it is submitted so that the variable storing form data becomes empty and wrap up your form processing block of codes to check if the form is empty.
As you probably know, ASP.NET Web Forms send POST requests back to the server and then re-render the Page in the same request. This is why we see the form re-submission message when we click "reload". To avoid this issue, we should employ the post-then-redirect pattern used by many web applications.
Use jQuery's submit event to handle the form submit, add return false; at the end of the submit handle function to prevent the page to reload. return false ; });
I would also like to point out that you can use a javascript approach, window.history.replaceState to prevent a resubmit on refresh and back button.
<script>
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}
</script>
Proof of concept here: https://dtbaker.net/files/prevent-post-resubmit.php (Link no longer works)
I would still recommend a Post/Redirect/Get approach, but this is a novel JS solution.
Use the Post/Redirect/Get pattern. http://en.wikipedia.org/wiki/Post/Redirect/Get
With my website, I will store a message in a cookie or session, redirect after the post, read the cookie/session, and then clear the value of that session or cookie variable.
You can prevent form resubmission via a session variable.
First you have to set rand() in a textbox and $_SESSION['rand'] on the form page:
<form action="" method="post">
<?php
$rand=rand();
$_SESSION['rand']=$rand;
?>
<input type="hidden" value="<?php echo $rand; ?>" name="randcheck" />
Your Form's Other Field
<input type="submit" name="submitbtn" value="submit" />
</form>
After that check $_SESSION['rand'] with textbox $_POST['randcheck'] value
like this:
if(isset($_POST['submitbtn']) && $_POST['randcheck']==$_SESSION['rand'])
{
// Your code here
}
Make sure you start the session on every file you are using it with session_start()
This method works for me well, and I think this is the simplest one to do this job.
The general idea is to redirect the user to some other pages after the form submission, which would stop the form resubmission on page refresh. Still, if you need to hold the user on the same page after the form is submitted, you can do it in multiple ways, but here I am describing the JavaScript method.
This method is quite easy and blocks the pop up asking for form resubmission on refresh once the form is submitted. Just place this line of JavaScript code at the footer of your file and see the "magic".
<script>
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}
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