How should you hook a session_start() when authoring a plugin?

Question

Learning more about sessions I've gathered that a session_start() should come directly after <?php per Where exactly do I put a SESSION_START? and I wanted to play around and create a plugin that would add a session_start() to header.php after it's <?php but after searching I've been inclusive with trying to figure out the appropriate procedure to do this.

I did search for session but I've seen a variety of Q&As that mostly seem to use:

• init: Session is not starting
• wp_head: Hook into wp_head(); in a plugin
• wp_loaded: Getting headers already sent error from plugin

So when authoring a plugin that relies on session to be added to header.php what is the appropriate hook for adding session_start()?

Answer 1

There is no regular output and hence no header sent before template_redirect on the front end. If you need sessions on the back end too, use the action wp_loaded to cover both.

Example:

add_action( 'template_redirect', function() {

    $status = session_status();

    if ( PHP_SESSION_DISABLED === $status ) {
        // That's why you cannot rely on sessions!
        return;
    }

    if ( PHP_SESSION_NONE === $status ) {
        session_start();
    }

    $_SESSION[ 'foo' ] = 'bar';
});

Keep in mind that using sessions adds a whole set of very complex problems to your code, including security, scalability (load balancers), and following time consuming support issues. I don't recommend it.

Answer 2

Here is also another solution for all kind of PHP versions what you can find inside CF Geo Plugin:

if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
    if(function_exists('session_status') && session_status() == PHP_SESSION_NONE) {
        session_start(array(
          'cache_limiter' => 'private_no_expire',
          'read_and_close' => false,
       ));
    }
}
else if (version_compare(PHP_VERSION, '5.4.0') >= 0)
{
    if (function_exists('session_status') && session_status() == PHP_SESSION_NONE) {
        session_cache_limiter('private_no_expire');
        session_start();
    }
}
else
{
    if(session_id() == '') {
        if(version_compare(PHP_VERSION, '4.0.0') >= 0){
            session_cache_limiter('private_no_expire');
        }
        session_start();
    }
}

With this solution you can prevent any problem with session and start it anytime you need.

Answer 3

We can use the easy way by init hook. Write this function in the function.php

function register_my_session() {
  if( !session_id() )
  session_start();
}
add_action('init', 'register_my_session');

after adding this function in function.php you can Set values in sessions like

$_SESSION['user_country'] = 'india';

Get session value

echo $_SESSION['user_country'];

for destroying session value

unset($_SESSION["user_country"]);