Woocommerce single_product_summary hook not working

Question

I'm trying to add my own custom fields to the single product summary after the main product's title output on my product page. I've looked into the woocommerce documentation (https://github.com/woothemes/woocommerce/blob/2.3.8/templates/content-single-product.php) and it looks like woocommerce_single_product_summary is my hook. So here's what I did:

// should hook into woocommerce single product summary and output info
function add_subtitle_to_product() {
    if (get_field('subtitle', get_the_ID())) {
        $output = '<h4>'.get_field('subtitle', get_the_ID()).'</h4>';
    }
    return $output;
}
   add_action( 'woocommerce_single_product_summary', 'add_subtitle_to_product', 6 );

And it wasn't working. I even made sure the get_field() call was returning true. So I decided to try a different approach:

// hook into woocommerce product summary and output test text
add_action('woocommerce_single_product_summary', function() {
    $output = '<p>Test</p>';
    return $output;
}, 7);

I tried this as a normal function with a name but that didn't work so I opted for an anonymous function that still isn't working.

What could be my issue?

Answer 1

In your first code block try changing return $output; with echo $output; and that should work provided $output is not empty :)

If you are trying to append your custom field to the product summary, this can be very well achieved using woocommerce_short_description filter hook. Please see below code:

function add_subtitle_to_product() {
    global $post;
    if (get_field('subtitle', get_the_ID()))
        return $post->post_excerpt . ''.get_field('subtitle', get_the_ID()).'';
    else
        return $post->post_excerpt;
}
add_action( 'woocommerce_short_description', 'add_subtitle_to_product', 10, 2 );