woocommerce_order_status_changed hook: getting old and new status?

How can I get the old status and new status of an order using the WooCommerce hook: `woocommerce_order_status_changed`?

This is my code, but only the `$order_id` is filled..

add_action('woocommerce_order_status_changed','woo_order_status_change_custom');
function woo_order_status_change_custom($order_id,$old_status,$new_status) {
//order ID is filled
//old_status and new_status never
//tested by logging the parameters
}

Now I can easily get the new status using this code:

$order = new WC_Order( $order_id );
$orderstatus = $order->status;

But how can I get the previous order status, since `$old_status` is empty?

Try this code. According to me it should work based on your comments.

add_action( 'save_post', 'wpse63478_save' );
function wpse63478_save() {

if(!current_user_can('manage_options'))
return false;
if(!is_admin())
return false;
if($_REQUEST['post_type'] != 'shop_order')
return false;
if($_REQUEST['post_ID']!='')
{
$orderId = $_REQUEST['post_ID'];
$order = new WC_Order( $orderId );
$currentStatus = $order->status;
$requestedStautus = $_REQUEST['order_status'];
if ( $requestedStautus== 'on-hold' and $currentStatus == 'completed') {
//Do your work here
}
}
}

I was looking for wc hooks and found this post. The reason the parameters are not set is that you're missing arguments in the add_action function. This function defaults to only one parameter. To have all three you should use:

add_action('woocommerce_order_status_changed', 'woo_order_status_change_custom', 10, 3);

The `10` is the default ordering for actions in Wordpress, and the last argument is the number of parameters that Wordpress should pass to the custom action.

Because you didn't added NUMBER of parameters at the end of add_action call. Here is correct line:

add_action('woocommerce_order_status_changed','woo_order_status_change_custom', 10, 3);

"10, 3" means "I want 3 parameters will be sent to my callback function". By default there is only 1 parameter (order_id) will be sent.