How to use session_start in Wordpress? - php

Question

I'm creating a bilingual site and have decided to use session_start to determine the language of the page using the following:
session_start();
if(!isset($_SESSION['language'])){
$_SESSION['language'] = 'English'; //default language
}
The problem with this is that it clashes with Wordpress and I get the following:
Warning: session_start() [function.session-start]: Cannot send session
cookie - headers already sent by (output started at
/home/neurosur/public_html/v2/wp-content/themes/default/header.php:8)
in /home/neurosur/public_html/v2/wp-content/themes/default/region.php
on line 13
Is there a way to get around this?

Answer 1

EDIT
Wordpress sends header info before the header.php file is run. So starting the session in the header.php may still conflict with the header info that wordpress sends. Running it on init avoids that problem. (From jammypeach's comment)
Write the following code in your functions.php file:
function register_my_session()
{
if( !session_id() )
{
session_start();
}
}
add_action('init', 'register_my_session');
Now if you want to set data in session, do like this
$_SESSION['username'] = 'rafi';

Answer 2

I've changed my original answer to the correct one from #rafi (see below).
Write the following code in your functions.php file:
function register_my_session()
{
if( !session_id() )
{
session_start();
}
}
add_action('init', 'register_my_session');

Answer 3

I found an interesting article by Peter here. I'm using the following code in my functions.php:
add_action('init', 'myStartSession', 1);
add_action('wp_logout', 'myEndSession');
add_action('wp_login', 'myEndSession');
function myStartSession() {
if(!session_id()) {
session_start();
}
}
function myEndSession() {
session_destroy ();
}
This destroys old session when user logs out then in again with different account.

Answer 4

Based on this answer and the answers given here, it's best to use the following code snippets:
For versions of PHP >= 5.4.0, PHP 7:
function register_my_session() {
if (session_status() == PHP_SESSION_NONE) {
session_start();
}
}
add_action('init', 'register_my_session');
Reference: http://www.php.net/manual/en/function.session-status.php
For versions of PHP < 5.4.0:
function register_my_session() {
if(session_id() == '') {
session_start();
}
}
add_action('init', 'register_my_session');
Reference: https://www.php.net/manual/en/function.session-id.php
I don't want to take any credits, I just felt like sharing this information would be helpful.

Answer 5

for PHP version 7.4
function register_my_session() {
if (session_status() === PHP_SESSION_NONE && session_status() !== PHP_SESSION_ACTIVE) {
#session_start();
}
}
add_action('init', 'register_my_session');

Answer 6

add_action('init', 'customSessionStart', 1);
add_action('wp_logout', 'customSessionDestroy');
add_action('wp_login', 'customSessionDestroy');
function customSessionStart()
{
if (!session_id()) {
session_start();
}
}
function customSessionDestroy()
{
session_destroy();
}
When you use this code, you may get the critical issue in the WP Site Health Status. The error says that;
A PHP session was created by a session_start() function call. This interferes with REST API and loopback requests. The session should be closed by session_write_close() before making any HTTP requests.
To suppress this error, you may make this revision when you want to start a session in the WP;
session_start([
'read_and_close' => true,
]);