Best way to trigger rewrite rules

Question

I typically call the rewrite rules with this action

add_action('init', 'add_my_rewrite_rules')

But what I do not like about it is that the rewrite rules are written every time an init action is triggered, which means pretty much every time a page is refreshed.

Is this the correct action to call the rewrite rules? Is there a better way of handling that? (i.e, no need to add the rules every time we trigger init)

Thanks.

Answer 1

init is the recommended hook and no, the rewrite rules will not be overwritten each time the hook fires or that the page is loaded, unless if you call flush_rewrite_rules() or WP_Rewrite::flush_rules() in your callback.

add_action( 'init', 'add_my_rewrite_rules' );
function add_my_rewrite_rules() {
    add_rewrite_rule( ... );
    flush_rewrite_rules(); // don't do this
}

So please don't do that, or do it only upon plugin/theme activation and deactivation — and if you don't already know, you can easily flush the rules by simply going to the Permalink settings admin page, without having to hit the Save Changes button.