Woocommerce REST API extending order response - wordpress

Question

I'm looking for a way to extend the wc-api/vX/orders/ reponse. I've added multiple custom fields to the checkout (for eg: relation number, delivery date etc). These meta are saved within the order (wp_postmeta table). But why are they not returned with the api?
Normally you can extend the api response with some code like:
add_action( 'rest_api_init', 'custom_register_api_fields' );
function custom_register_api_fields() {
register_rest_field( 'shop_order','relation_number',
array(
'get_callback' => 'custom_api_meta_callback',
'update_callback' => null,
'schema' => null,
)
);
}
/**
*
* #param array $object Details of current post.
* #param string $field_name Name of field.
* #param WP_REST_Request $request Current request
*
* #return mixed
*/
function custom_api_meta_callback( $object, $field_name, $request ) {
return get_post_meta( $object[ 'id' ], $field_name, true );
}
But when I test the response (with Postman and the php lib), my-website.co/wc-api/v2/orders the custom meta are not visible.
Is there a way to register api fields for the wc-api?
Tnx!

Answer 1

i have the same requirement, add new value to "line_items" in order response
am using wc api v2
https://website.com/wp-json/wc/v2/orders
function get_product_order_image( $response, $object, $request ) {
if( empty( $response->data ) )
return $response;
$order_pid= $response->data['line_items'][0]['product_id'];
$l_w_product_meta = get_post_meta($response->data['line_items'][0]['product_id']);
$order_imgUrl= wp_get_attachment_url( $l_w_product_meta['_thumbnail_id'][0], 'full' );
$response->data['line_items'][0]['cover_image'] = $order_imgUrl;
return $response;
}
add_filter( "woocommerce_rest_prepare_shop_order_object", array( $this, "get_product_order_image"), 10, 3 );
Result
cover image added to line item result
i hope this will help someone in future.

Answer 2

REST API hook for add new value (product image) to "line_items" in order response for simple product and variable product both
Also Use for multiple products
function get_product_order_image( $response, $object, $request ) {
if( empty( $response->data ) )
return $response;
$images = array();
foreach($response->data['line_items'] as $key => $productItems){
$productID = $productItems['product_id'];
$variationID = $productItems['variation_id'];
if($variationID == 0){
$thumbnailID = get_post_meta( $productID, '_thumbnail_id', true);
$attachment = wp_get_attachment_image_src($thumbnailID, 'woocommerce_thumbnail' );
$image = $attachment[0];
}else{
$variation = new WC_Product_Variation( $variationID );
$image_id = $variation->get_image_id();
$attachment = wp_get_attachment_image_src($image_id, 'woocommerce_thumbnail' );
$image = $attachment[0];
}
$response->data['line_items'][$key]['image'] = $image;
}
return $response;
}
add_filter( "woocommerce_rest_prepare_shop_order_object", "get_product_order_image", 10, 3 );
Request:
wp-json/wc/v3/orders
wp-json/wc/v3/orders/XXX
wp-json/wc/v3/orders/?customers=XXX