WordPress + Woocommerce + Yoast: add a custom variable to the SEO title

The default list of variables (<http://docs.mainwp.com/available-wordpress-seo-yoast-variables/>) did not suffice, as there is no link with Woocommerce.

Luckely it is very easy to add some code to your custom theme. Here is how I did it:

1. Add a functions.php file to your (custom) theme (if it does not exist yet).

2. write your custom function which returns the value you want (i.c. the price of the product)

/**
* retrieve_price_replacement()
* Retrieves the price of the current product
*
* @return string
*/
function retrieve_price_replacement() {
  // Check if the class exists, or we could get errors
  if (class_exists('WC_Product')) {
    $product = new WC_Product(get_the_ID());
    if (isset($product->price)) {
      return "{$product->price} EUR";
    }
  }

  // Fallback: return empty string
  return '';
}

3. Register your custom function as a variable

/**
* register_custom_extra_replacements()
*
* Register extra SEO replacements for the page title
*/
function register_custom_extra_replacements() {
  wpseo_register_var_replacement( '%%price%%', 'retrieve_price_replacement', 'advanced', 'Get the price for the loaded product' );
}

4. Hook the register function on to the action “wpseo_register_extra_replacements”

add_action('wpseo_register_extra_replacements', 'register_custom_extra_replacements');

You can now easily add extra variables by adding them to the register_custom_extra_replacements() function.

All code above goes into the functions.php file.

Happy coding!