Programmatically add existing pages and subpages to Appearance Menu

Question

I have inherited a site with over 600 pages/subpages. I plan to use a plugin to change the way the navigation displays but it requires the pages to be in the Appearance -> Menu in this page: /wp-admin/nav-menus.php

I looked at other answers that were similar, and they were either old, incomplete, or non-programmatic. The solution I need should make it so the empty menu gets populated with all of the 600 pages/subpages. When that's done the plugin I'm using can style the menu in the way that I like.

Answer 1

I wouldn't use such plugin, I'm afraid...

wp_nav_menu stores every menu item as post. So if you add 600 items to menu, then there are 600 posts queried every time page loads.

And even worse - every such page needs some processing, getting meta data and passing through recursive Walker class...

It will kill performance of your site...