php - Woocommerce Gateway Integration Payment Status not updating -

i have set custom woocommerce off-side payment gateway, communication website gateway works fine. user gets redirected gateway , after payment gets returned (by woocommerce) defined return url.

in api documentation of gateway, says payment gateway add query string variable return url. variable can have following values:

response=approved response=declined response=error 

in documentation exampple: if backurl = http://www.test.com/return.asp response http://www.test.com/return.asp?response=approved

to process order have created code below (first state of response=approved) however, order status not updated, when test it. hope can point me in right direction find error.

on top of gateway have extended query_vars with:

function add_query_vars_filter( $vars ){ $vars[] = "response"; return $vars; } add_filter( 'query_vars', 'add_query_vars_filter' );     

after sending user gateway have function handle , process query string in return url:

function check_example_response(){          global $woocommerce;              $transaction_id = get_query_var( 'response' );              $order          = new wc_order( $order_id );                  // check if payment successful                 if ($transaction_id == 'approved') {                              //update order status                             $order->update_status( 'processing', 'payment received, order being processed.' );                              //add admin order noote                             $order->add_order_note('payment via example gateway<br />transaction id: '.$order);                              //add customer order note                             $order->add_order_note('payment received.<br />your order being processed.<br />we shipping order soon.<br />transaction id: '.$order, 1);                              $message = 'thank shopping us.<br />your transaction successful, payment received.<br />your order being processed.';                             $message_type = 'success';                         }                          // reduce stock levels                         $order->reduce_order_stock();                          // empty cart                         wc()->cart->empty_cart();  }} 

i have registered function with:

add_action( 'woocommerce_api_wc_example', array( $this, 'check_example_response' ) ); 

wordpress not give hints in debug mode, right quite frustrated , hope can me.

thank you!