Cannot access class properties from ajax call in wpordrpess

Question

I have a problem with calling a class method from inside a wp_ajax_function. My code looks like this:

 class Cart {

    public $cart_content;
    public $cart_id;
    public $db;

    public function __construct() {
        $this->db           = $GLOBALS['wpdb'];

        add_action( 'wp_ajax_update_cart', array($this, 'update_cart') );
        add_action( 'wp_ajax_nopriv_update_cart', array($this, 'update_cart') );
    }

    public function get_cart_content($cart_id = false) {
        if( !$cart_id ) $cart_id = $this->cart_id;

        $content = $this->db->get_row( $this->db->prepare("SELECT content FROM {$this->db->prefix}$this->cart_table WHERE cart_id = '%s'", $cart_id) );
        $this->cart_content = $content ? unserialize($content->content) : $content;

        return $this->cart_content;
    }

    public function update_cart() {
        $items = $_POST['items'];

        wp_send_json( $this->get_cart_content()) );
    }

The problem is that I cannot access class properties inside updat_cart() function. So when I call get_cart_contents() method it return null. Thanks in advance for any help. Rafal

Answer 1

The problem was caused by another method inside the class:

     public function create_cart_id() {
        if( is_user_logged_in() ) {
            $this->create_logged_in_cart_id();
        }else {
            $this->create_non_logged_in_cart_id();
        }

        return $this->cart_id; - adding that line solved the problem
    }

This method generates the $cart_id, but it didn't return its value, so it was not accessible from outside and returned null.