What are best practices for handling form data in PHP to avoid issues with session variables and POST values?

When handling form data in PHP, it's important to avoid conflicts between session variables and POST values by properly checking and setting the values. One way to do this is to check if the form has been submitted using the POST method before setting session variables based on the form data. This ensures that session variables are not overwritten by form data unintentionally. 

<?php
session_start();

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process form data
    $username = $_POST['username'];
    $password = $_POST['password'];

    // Validate form data
    // ...

    // Set session variables based on form data
    $_SESSION['username'] = $username;
    // ...
}
?>

Keywords

session variables POST values form data PHP handling

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