Code-Snippets-Functions/Execute a function on a child site/WooCommerce/display-first-gallery-image-as-product-thumbnail-in-cart.txt

function filter_woocommerce_cart_item_thumbnail( $thumbnail, $cart_item, $cart_item_key ) {
    // Get product
    $product = $cart_item['data'];
    
    // Get gallery image ids
    $attachment_ids = $product->get_gallery_image_ids();
    
    // NOT empty
    if ( ! empty ( $attachment_ids ) ) {
        // First
        $attachment_id = $attachment_ids[0];
        
        // New thumbnail
        $thumbnail = wp_get_attachment_image( $attachment_id, 'woocommerce_thumbnail' );
    }
    
    return $thumbnail;
}
add_filter( 'woocommerce_cart_item_thumbnail', 'filter_woocommerce_cart_item_thumbnail', 10, 3 );