Custom Query Filter for Elementor Posts by relationship field (ACF)

Question

I have a custom post type setup called 'Artists'. Each Single Artist is a page (artist profile if you wish), has a list of products that are associated with that artist via the relationship field type through Advanced Custom Fields (ACF). I need the products to be displayed within their categories on the artist page. So within Elementor I need to specify a 'Query Filter ID' to simply split the products into categories.

What I have tried so far

I am trying to display only products from a certain category in a list via a custom query as I need to generate a Query ID.

I've been trying a bunch of different ways to do this but now I'm at a loss. The latest code I have is here... what am I missing?

/** Product category 'SOFTWARE' **/
add_filter( 'software_product', 'product_category_software' );

function product_category_software( $variable ) {

    $query_args = array(
       'post_type' => 'product',
       'tax_query' => array(
            array(
                'taxonomy' => 'category',
                'field'    => 'slug',
                'terms'    => 'software', 
            ),
        ),
     );
return $variable;
}

Answer 1

Answer

You need to use this

https://developers.elementor.com/custom-query-filter/#Using_the_Custom_Filter

arbitrary_name_query_id - the QUERY ID that you fill in the Elementor field,

the code to be placed within functions.php:

add_action( 'elementor/query/arbitrary_name_query_id', function( $query ) {
    $meta_query = $query->get( 'meta_query' ); 
    $meta_query[] = [ 
        'key'     => 'acf_key', // put ACF relationship field name 
        'value'   => get_the_ID(), 
        'compare' => '=', 
    ]; 
    $query->set( 'meta_query', $meta_query ); 
} ); 

Regarding to the given code

First of all, as Wordpress Documentation on filters says:

They (i.e. filters) provide a way for functions to modify data of other functions.

Which means that the filter function, in this case it's product_category_software, receives data that subsequntly modifies and returns it back:

add_filter( 'software_product', 'product_category_software' );
function product_category_software( $variable ) { // receive $variable

    /**
     * Modify $variable here
     */

    return $variable; // return modified $variable
}

In your case product_category_software doesn't modify what receives, but introduces new peace of data $query_args which makes no sence, since it is not going to be returned.

Secondly, the first argument of the add_filter function should be an existent filter name, the software_product is not.

Thirdly, the correct name of the taxonomy of product categories is product_cat.

Getting products from a certain category

Aproach #1 Modfying main query with pre_get_posts

function your_arbitrary_name( $query ) { // receive
    if ( ! is_admin() && is_post_type_archive( 'product' ) && $query->is_main_query() ) {
        $tax_query = array(
            array(
                'taxonomy' => 'product_cat',
                'field'    => 'slug',
                'terms'    => array( 'software' ),
            )
        );

        $query->set( 'meta_query', $tax_query ); // modify
    }
    return $query; // and return
}
add_action( 'pre_get_posts', 'your_arbitrary_name', 20 );

Aproach #2 Use wc_get_products or WC_Product_Query

Example, use in your Controller or even in the template:

$args = array(
    'category' => array( 'software' ),
);
$products = wc_get_products( $args );

Read the Docs about wc_get_products and WC_Product_Query