Add a custom menu item that supports wildcards

Question

I am not very familiar with Wordpress terminology yet, so this may be why my Google results come back empty but I guess this is a question that troubles a lot of developers with Drupal background that move to Wordpress.

The short version:

"Is there a way to programmatically add a menu item like mywordpresssite.com/my/custom/url/%/% (where % are wildcards) and define what this page will return in my code?"

The extended version:

In Drupal there is a hook called hook_menu where you can define a menu path like the one mentioned above and a callback function that will take the wildcards as arguments.

What I'm trying to do here is simple: create a button on every post of the site; when this button is clicked in a specific post, it will do a simple GET request via AJAX to a menu item like: mywordpresssite.com/ajax-calls/%current_post_id which will allow me to do some further processing of the specific post in the background.

I hope that the above makes sense. If this is not the way that things work in Wordpress, please provide any resources as to how I should go about approaching the task at hand.

Answer 1

This code can be used after the new post was saved. Otherwise there is no post object at the time.

Please pay attention that the code was not tested.

<?php
// get post ID from the URL query
$post_id = $_GET['post'];

// get post object
$new_item_to_add = get_post($post_id, OBJECT);

// get menu to add the item into (change to the relevant slug, ID, or name)
$existing_menu = wp_get_nav_menu_object('test-nav-menu-slug');
$existing_menu_id = $existing_menu->term_id;

$new_menu_item_data =  array(
    'menu-item-db-id' => $menu_item_db_id, // default 0, creates a new one
    'menu-item-object-id' => $post_id,
    'menu-item-object' => '', //default
    'menu-item-parent-id' => 0, //default
    'menu-item-position' => 0, //default
    'menu-item-type' => $new_item_to_add->post_type,
    'menu-item-title' => $new_item_to_add->post_title,
    'menu-item-url' => get_permalink($post_id),
    'menu-item-description' => '', //default
    'menu-item-attr-title' => '', //default
    'menu-item-target' => '', //default
    'menu-item-classes' => '', //default
    'menu-item-xfn' => '', //default
    'menu-item-status' => 'publish',
);

wp_update_nav_menu_item($existing_menu_id, $menu_item_db_id = 0, $new_menu_item_data);

See wp_update_nav_menu_item code reference.

Also, there is a worse way. You can alter the menu on-the-fly. This will not update the menu:

<?php
function wpse267737_add_nav_menu_items($nav_menu_items) {

    // get post ID from URL
    $post_id = $_GET['post'];

    // get current post data
    $link_url = get_permalink( $post_id );
    $link_anchor =  get_the_title( $post_id );

    // build new menu item
    $new_menu_item = '<li><a href="' . $link_url . '">' . $link_anchor . '</a></li>';

    // concatenate existing items and new
    $nav_menu_items .= $new_menu_item;

    return $nav_menu_items;
}
// change TEST-MENU-SLUG to the relevant menu slug
add_filter( 'wp_nav_menu_TEST-MENU-SLUG_items', 'wpse267737_add_nav_menu_items' );

See wp_nav_menu_items reference.