CODEWITHSUNDEEP
php
user4099209
user4099209

Reputation:

Do not submit same data twice php

How would I check in PHP if the exact same data has not been already sent?

This will prohibit users (accidently) sending a contact form twice with the same data on my website!.

Thanks!

Upvotes: 0

Views: 234

Answers (1)

Alexander
Alexander

Reputation: 323

You can for example serialize the form data and store it in a session variable. Upon receiving form data, first check if the same data is already present in the session. You can also add a random number to the form as hidden input field which is also stored in $_SESSION["rand"]. Upon the first submit, the random number is checked for equality and then removed (or changed) in the session array. This way, a single form can only be used once, upon a second submit, the number will be different and not accepted anymore.

When generating a form:

$_SESSION["rand"] = rand();

And add in the form:

<input type='hidden' name='rand' value='{$_SESSION["rand"]}' />

Upon receiving, check:

if ( $_SESSION["rand"] === $_POST["rand"]) {
    $_SESSION["rand"] = false;
    // continue with stuff...

Of course, with this layout, a single user can only open a single form at the same time, since opening a second form will overwrite the random number. An even better approach would be to create a individual session key and value combination for each form, thus two forms will not overwrite each other.

Upvotes: 1

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