Woocommerce add_filter在某些时候隐藏统一费率方法而不能使用var_dump变量

Question

Completely new to Woocommerce/wordpress here. On the cart page mydomain.local/cart What filter should I use to show/hide a flat rate shipping method at certain times. From admin I managed to add an extra flat rate method and named it "Next day". Now I would like to show that flat rate method only before 4PM. I tried in functions.php

add_filter( 'woocommerce_package_rates', 'custom_change_shipping', 10);

function custom_change_shipping($rates) {
    var_dump($rates);
}

Nothing seems to change and also I cant seem to debug the $rates variable as nothing is outputted when var_dump($rates);. I tried it both anonymous and as an admin but nothing seems to work.

Answer 1

Thanks @LoicTheAztec for confirming whether I was using the right filter. My other problem was that I was not able to output var_dump on the /cart page.

I found out that I need to clear my "cart cache" by going to woocommerce->settings->shipping and in the region, disable then enable again and click on save changes. By doing this I could see my output from var_dump.