If else statement for EU countries in filter for WooCommerce breaks REST API

Question

Update: By wrapping my object in this if statement it doesn't break the API call:

if ( WC()->customer ) {
}

---

Im using a plugin that displays all prices the same regardless of VAT in WooCommerce. This works well - but I only need this for EU countries.

The plugin has a filter:

add_filter('wc_aelia_tdbc_keep_prices_fixed', function($keep_prices_fixed): bool {
    if() {
        $keep_prices_fixed = true;
    }    
    return $keep_prices_fixed;
});

What I got so far:

add_filter('wc_aelia_tdbc_keep_prices_fixed', function($keep_prices_fixed): bool {
    
            $countries = new WC_Countries();
        $eu_countries = $countries->get_european_union_countries();
    
       if ( in_array( WC()->customer->get_billing_country(), $eu_countries ) ) {
        $keep_prices_fixed = true;
        } else {
        $keep_prices_fixed = false;
        }
    
    return $keep_prices_fixed;
});

On the front-end this works well - it only applies the flat prices for EU countries. It does however break the WooCommerce REST API with an error:

Uncaught Error: Call to a member function get_billing_country() on null

I assume the WC()->customer->get_billing_country() object is not being initialised in the API call.

How do I check if this object are initialised, before accessing it?

Answer 1

By default Woocommerce will not load user session data in rest api to improve the performance. For that you need to initialize the user session, then get the customer info.

if ( null === WC()->session ) {
   $session_class = apply_filters( 'woocommerce_session_handler', 'WC_Session_Handler' );
    WC()->session = new $session_class();
    WC()->session->init();
}
WC()->customer = new WC_Customer( get_current_user_id(), true );
echo WC()->customer->get_billing_country();