Skip activation page on MultiSite - Activate header

skip activation page on multisite

add_action( 'activate_header', 'check_activation_key_redirect_to_page' );
/**
 * Check the wp-activate key and redirect the user to home page.
 */
function check_activation_key_redirect_to_page() {
	// We check if the key is not empty
	if ( ! empty($_GET['key']) && ! empty($_POST['key']) ) {
		
		$key = !empty($_GET['key']) ? $_GET['key'] : $_POST['key'];
		
		// Activates the user and send user/pass in an email 
		$result = wpmu_activate_signup($key);
		
		if ( ! is_wp_error($result) ) {
			extract($result);
			$user = get_userdata( (int) $user_id);
			
			// Start session if it was not started
			if ( ! session_id() )
				session_start();
			
			// Save the user object to the session
			$_SESSION['my_active_user_variable'] = $user;
			
			// Redirect to the network home url
			wp_redirect( network_site_url() );
			exit;
		}
	}
}