WooCommerce add sorting filter by attribute

Question

Im trying to add an additional sorting method by an attribute 'brand'

Its adding to the front end but I have no idea what the meta key would be for an attribute.

function theme_catalog_orderby( $catalog_orderby_options ) {
    $catalog_orderby_options['brands'] = __( 'Sort by brands', 'textdomain' );
 
    return $catalog_orderby_options;
}
 
add_filter( 'woocommerce_catalog_orderby', 'theme_catalog_orderby' );

/**
* Returns an array of arguments for ordering products based on the selected values.
*
* @uses woocommerce_get_catalog_ordering_args hook
* @return array
*/
function theme_get_catalog_ordering_args( $args ) {
  
  $orderby_value = isset( $_GET['orderby'] ) ? woocommerce_clean( $_GET['orderby'] ) : apply_filters( 'woocommerce_default_catalog_orderby', get_option( 'woocommerce_default_catalog_orderby' ) );
    if ( 'sale' == $orderby_value ) {
 
        $args['meta_key'] = '_brands';
        $args['orderby'] = 'meta_value_num';
        $args['order'] = 'DESC';
 
    }
 
    return $args;
}
 
add_filter( 'woocommerce_get_catalog_ordering_args', 'theme_get_catalog_ordering_args' );

Postman result

 "attributes": [
        {
            "id": 2,
            "name": "brands",
            "position": 0,
            "visible": true,
            "variation": false,
            "options": [
                "Rice"
            ]
        }

Tried

"attributes": [{"name": "brands"}] 

Need to know how to target the attribute name. Thanks alot

Answer 1

Product attributes are saved in a serialized array under the post_meta table with meta_key _product_attributes. The problem is that your brands attribute is contained there with a prefix like pa_brands. This makes filtering directly with an SQL query somewhat hard.