Post Grid - Related post by current post categories

gistfile1.txt

function post_grid_query_args_20200429($query_args, $args)
{

    $current_post_id = get_the_ID();

    $taxonomy = "category";
    $post_categories = get_the_terms($current_post_id, $taxonomy);

    $tax_query = isset($query_args['tax_query']) ? $query_args['tax_query'] : [];


    $term_ids = [];

    foreach ($post_categories as  $category) {

        $term_id = isset($category->term_id) ? $category->term_id : '';

        if (!empty($term_id)) {
            $term_ids[] = $term_id;
        }
    }



    if (!empty($term_ids)) {
        $tax_query[] = array(
            'taxonomy' => $taxonomy,
            'field'    => 'term_id',
            'terms'    => $term_ids,
            'operator'    => "IN",
        );
    }




    $extra_query = array(

        'tax_query' => $tax_query,

    );

    return array_merge($query_args, $extra_query);
}

add_filter('post_grid_query_args', 'post_grid_query_args_20200429', 10, 2);