how to use $_POST to change some contents forever

April 18, 2022

I am trying to populate data from a website to another wensite:
a.html:

<form action="b.php" method="post">
<textarea id="myProjects" name="mp"></textarea>
<input id="submit" type="submit" value="Submit" />
</form>

in b.php:

<?php $content=$_POST['mp'];
echo "you entered ".$content;
?>

This works in a very strange way, when I click submit button, I am directed to the b.php page, and I can see what I entered. But if I reload this page, not refresh, my contents disappear, and throwWarning: Undefined array key "mp" It looks like data received from $_POST is "temporarily" stored. I am new to PHP, so I am not sure how can I figure it out.

>Solution :

You can use the PHP SESSION feature to keep the data persistent:

in b.php:

<?php
   // Start the session
   session_start();

   // save the input var as a SESSION property
   if (isset($_POST['mp'])) {
      $_SESSION['content'] = $_POST['mp'];
   }

   // display the property
   echo "you entered " . $_SESSION['content'];