How to use a WooCommerce action hook?

Question

I am wondering how you would implement the following hook.

do_action( 'woocommerce_process_product_meta_' . $product_type, $post_id );

What is the correct way to call a call the action from a plugin file. Bellow is the code that I am currently using but its not working.

global $post, $thepostid, $woocommerce;

function new_post_meta () {
    if (isset($_POST['location'])) 
        update_post_meta( $post_id, 'location', json_encode($_POST['location']) );      
}

add_action( 'woocommerce_process_product_meta_' .$product_type, 'new_post_meta' );

Answer 1

For example you have two product types: product1 and product2. Then you will have two action calls: woocommerce_process_product_meta_product1 and woocommerce_process_product_meta_product2. So you need to add your hooks like this:

function new_post_meta1 () {
    if (isset($_POST['location'])) 
        update_post_meta( $post_id, 'location', json_encode($_POST['location']) );       
}
add_action( 'woocommerce_process_product_meta_product1', 'new_post_meta1' );

function new_post_meta2 () {
    if (isset($_POST['location'])) 
        update_post_meta( $post_id, 'location', json_encode($_POST['location']) );       
}
add_action( 'woocommerce_process_product_meta_product2', 'new_post_meta2' );

Answer 2

If you don't intend your meta field to be specific to a particular product type you can do the following ( which is what I do in my own WooCommerce extension ).

function new_post_meta () {
    if (isset($_POST['location'])) 
        update_post_meta( $post_id, 'location', json_encode($_POST['location']) );      
}

add_action( 'woocommerce_process_product_meta', 'new_post_meta' );