Assign a tag programatically for stock status when product is saved in WooCommerce backend

Question

I have created 3 tags 1.

• Backorder (id 111)
• In stock (id 112),
• Out of stock (id 113)

I would like these tags to be auto-assigned based on availability.

If I am able to get this working, I'll be using the woocommerce_admin_process_product_object, woocommerce_product_quick_edit_save, woocommerce_product_set_stock, woocommerce_variation_set_stock to capture the possible scenarios for stock status changes.

Below is what I have tried but it gives me a fatal error. If I do not use the if condition, then the tags get assigned but it does not meet my objective. Any advice?

add_action( 'woocommerce_admin_process_product_object', 'mycode_woocommerce_backorder_tag', 10, 2 );
function mycode_woocommerce_backorder_tag ($wc_get_product, $product) {
    if ($product->managing_stock() && $product->is_on_backorder(1)) {
        $wc_get_product->set_tag_ids(array(111));
        $wc_get_product->save();
        //wp_set_object_terms ($post_id, 'onbackorder', 'product_tag');
    }
}

Answer 1

woocommerce_admin_process_product_object hook has only 1 argument, which is $product

$product->save(); is also not necessary, because this happens automatically

Copied from admin/meta-boxes/class-wc-meta-box-product-data.php

/**
 * Set props before save.
 *
 * @since 3.0.0
 */
do_action( 'woocommerce_admin_process_product_object', $product );

$product->save();

---

So to answer your question, you get:

// When product is saved in WooCommerce backend
function action_woocommerce_admin_process_product_object( $product ) {
    // managing_stock() - returns whether or not the product is stock managed.
    // on_backorder() – check if a product is on backorder.
    if ( $product->managing_stock() && $product->is_on_backorder(1) ) {
        // Product set tag ids
        $product->set_tag_ids( array( 111 ) );
    }
}
add_action( 'woocommerce_admin_process_product_object', 'action_woocommerce_admin_process_product_object', 10, 1 );