Order status still “Pending Payment” after successful payment (Custom payment gateway) - wordpress

Question

I was develop a custom payment gateway for woocommerce, everything is good but after payment success the order still "pending payment"
In the __construct() function I check for payment provider respond
<?php
//when payment done and redirected with payment reference code
if(isset($_REQUEST['transaction_id'])){
paytabs_set_cookie('transaction_id', $_REQUEST['transaction_id']);
$order = new WC_Order($order_id);
$this->order = $order;
$this->complete_transaction($order->get_id(), $_REQUEST['transaction_id']);
}
and here is the complete_transaction() function
<?php
/*
When transaction completed it is check the status
is transaction completed or rejected
*/
function complete_transaction($order_id, $transaction_id) {
global $woocommerce;
$order = new WC_Order( $order_id );
$request_string=array(
'secret_key' => $_COOKIE['secret_key'],
'merchant_email' => $_COOKIE['merchant_email'],
'transaction_id' => $transaction_id,
'order_id' => $order_id
);
$gateway_url=$this->liveurl.'apiv2/verify_payment_transaction';
$getdataresponse=$this->sendRequest($gateway_url, $request_string);
$object=json_decode($getdataresponse, true);
if (isset($object->response_code)) {
//if get response successfull
if($object->response_code == '100'){
// thankyou and set error message
$this->msg['class'] = 'woocommerce_message';
$check=$order->payment_complete();
// Reduce stock levels
$order->reduce_order_stock();
// Remove cart
$woocommerce->cart->empty_cart();
wc_add_notice( '' . __( 'Thank you for shopping with us. Your account has been charged and your transaction is successful.
We will be shipping your order to you soon.', 'woocommerce' ), 'success' );
wp_redirect( $this->get_checkout_order_received_url( $order ) );
exit;
}else{
// Change the status to pending / unpaid
$order->update_status('failed', __('Payment Cancelled', 'error'));
// Add error for the customer when we return back to the cart
$message=$object->result;
wc_add_notice( '<strong></strong> ' . __($message, 'error' ), 'error' );
// Redirect back to the last step in the checkout process
wp_redirect( $this->get_cancel_order_url( $order ) );
exit;
}
}
}
But the order status still "pending payment".
now I need to change the order status to "Completed" after check the payment provider respond.

Answer 1

Fixed
The problem because of this line
wp_redirect( $this->get_checkout_order_received_url( $order ) );
it must be $order instead of $this so the line is like this
wp_redirect( $order->get_checkout_order_received_url( $order ) );