Adding conditional menu items to WordPress menus with custom type labels.

class-mjj-menu-functions.php

<?php
/**
 * Conditional menu items and sane ways to add them to menus in the admin area.
 *
 * @package mjj_menu
 */
class MJJ_Menu_Functions {

	/**
	 * Our new menu types
	 *
	 * @var array
	 */
	public $mjj_menu_types;

	/**
	 * Sets up common variable and adds in hooks.
	 *
	 * @return void
	 */
	public function init() {

		// Use mjj-logged-in- as the prefix to check for logged in users.
		// Use mjj-subs- as the prefix to check for subscribers.
		// The last bit will tell you how to get the permalink from the id.
		$this->mjj_menu_types = [
			'mjj-logged-in-page' => 'Shows for logged in users',
			'mjj-subs-cat'       => 'Shows for subscribers',
			'mjj-subs-page'      => 'Shows for subscribers',
		];

		// This is what filters the menu items shown on the public facing site.
		add_filter( 'wp_nav_menu_objects', array( $this, 'dynamic_menu_items' ), 10, 2 );

		// This adds a new metabox in the admin section from which you can choose menu items to add to your menu.
		add_action( 'admin_head-nav-menus.php', array( $this, 'add_menu_metabox' ) );

		// This handles the new label
		add_filter( 'wp_setup_nav_menu_item', array( $this, 'nav_type_labels' ) );

		// Re-add the url to the menu item.
		add_action( 'wp_update_nav_menu_item', array( $this, 'add_back_url' ), 10, 3 );
	}

	/**
	 * Filter out conditional menu items if the user should not see them.
	 *
	 * @param array  $menu_items The menu items, sorted by each menu item's menu order.
	 * @param object $menu_args The menu object.
	 * @return array The final html for the menu.
	 */
	public function dynamic_menu_items( $menu_items, $menu_args ) {

		foreach ( $menu_items as $key => $item ) {
			$type = $item->type;
			// If a user is not logged in, unset the "mjj-logged-in" type menu items so they don't show in the menu.
			if ( strpos( $type, 'mjj-logged-in' ) === 0 ) {
				$is_logged_in = is_user_logged_in();
				if ( ! $is_logged_in ) {
					unset( $menu_items[ $key ] ); // If the user is not logged in, remove the link.
					continue;
				}
			}
			// If a user has not bought a subscription, unset the "mjj-subscription-member" type menu items so they don't show in the menu.
			if ( strpos( $type, 'mjj-subs-' ) === 0 ) {
				$user_id              = get_current_user_id();
				$is_subscription_user = mjj_user_has_subscription( $user_id ); // Made up function for the purpose of this post.
				if ( ! $is_subscription_user ) {
					unset( $menu_items[ $key ] );
					continue;
				}
			}
		}

		return $menu_items;
	}

	/**
	 * This takes the object id and object type and returns the correct link.
	 *
	 * @param string|int $object_id Will be used as an int. The id of the object the menu item is for.
	 * @param string     $object_type The type of the object the menu item is for.
	 * @return string The url for the menu item.
	 */
	private function get_link( $object_id, $object_type ) {
		$url = '';
		switch ( $object_type ) {
			case 'term':
				$url = get_term_link( (int) $object_id );
				break;
				// A note on get_term_link: if you want to use an id, it *must* be an int, otherwise it treats it as the slug.
				// See: https://developer.wordpress.org/reference/functions/get_term_link/ .
			case 'post':
				$url = get_permalink( $object_id );
				break;
		}
		return $url;
	}

	/**
	 * Adds the metabox to the nav menu list.
	 *
	 * @return void
	 */
	public function add_menu_metabox() {
		add_meta_box( 'mjj_course_conditional_nav_links', __( 'MJJ Conditionals', 'mjjmenu' ), array( $this, 'menu_metabox' ), 'nav-menus', 'side', 'low' );
	}

	/**
	 * Output menu metabox.
	 *
	 * @return void
	 */
	public function menu_metabox() {

		// A contact page for subscribers only.
		$member_contact_page   = get_page_by_path( 'member-contact-us', OBJECT );
		$one_off_things_to_add = [
			'home_on_checkout'    => [
				'label'       => 'Conditional home button for logged in users', // Only logged in people get the home button. Ha.
				// Label is used in the checklist.
				'title'       => 'Home',
				'class'       => 'mjj-show-logged-in',
				'id'          => get_option( 'page_on_front' ), // id is the id of the page.
				'type'        => 'mjj-logged-in-page',
				'object-type' => 'post',
				// The type. 'mjj-logged-in' tells me it's for logged in users, 'page' tells me how to get the url.
				// We'll use id and the type to get the link with get_permalink().
			],
			'back_to_your_course' => [
				'label'       => 'Member contact page (shows only for paid subscribers)',
				'title'       => 'Contact us',
				'class'       => 'mjj-subscription-members',
				'id'          => $member_contact_page->ID, // id is the id of the page.
				'type'        => 'mjj-subs-page',
				'object-type' => 'post',
				// The type. 'mjj-subs' is the prefix which tells me to limit to subscribers. 'page' tells me how to get the url.
				// We'll use id and the type to get the link with get_permalink().
			],
		];

		// This gets a list of categories which are only available to subscribers.
		$something                    = new Something();
		$subscription_only_categories = $something->get_protected_categories; // Made up function for illustrative purposes.

		// Start with an empty array of them.
		$add_sub_cats = [];
		foreach ( $subscription_only_categories as $index => $row ) {
			$term = get_term( $row->category_id );
			$add_sub_cats[ 'cat_id_' . (int) $row->category_id ] = [
				'label'       => esc_html( $term->name . ' (shows only for paid subscribers)' ),
				'title'       => esc_html( $term->name ),
				'class'       => 'mjj-subscription-members',
				'id'          => $term->term_id, // id is the id of the term.
				'type'        => 'mjj-subs-cat',
				'object-type' => 'term',
				// The type. 'mjj-subs' is the prefix which tells me to limit to subscribers. 'cat' tells me how to get the url.
				// We'll use id and the type to get the link with get_term_link().

			];
		}

		if ( ! empty( $add_sub_cats ) ) {
			// We'll build the menu checklist from the merged arrays.
			$things_to_add = array_merge( $one_off_things_to_add, $add_sub_cats );
		}
		?>
		<div id="mjj-conditional-menu-items" class="posttypediv">
			<div id="tabs-panel-mjj-conditionals" class="tabs-panel tabs-panel-active">
				<ul id="mjj-conditional-checklist" class="categorychecklist form-no-clear">
				<?php
				$i = -100; // I think this needs to be unique? Fingers crossed no one else is using -100 as a starting point.
				foreach ( $things_to_add as $item => $details ) :
					?>
						<li>
							<!-- The label in the checklist *only* -->
							<label class="menu-item-title">
								<input type="checkbox" class="menu-item-checkbox" name="menu-item[<?php echo esc_attr( $i ); ?>][menu-item-object-id]" value="<?php echo (int) $details['id']; ?>" /> <?php echo esc_html( $details['label'] ); ?>
							</label>
							<!-- Adds the type to the menu item -->
							<input type="hidden" class="item-type" name="menu-item[<?php echo esc_attr( $i ); ?>][menu-item-type]" value="<?php echo esc_attr( $details['type'] ); ?>" />
							<!-- Adds the default title to the menu item -->
							<input type="hidden" class="menu-item-title" name="menu-item[<?php echo esc_attr( $i ); ?>][menu-item-title]" value="<?php echo esc_html( $details['title'] ); ?>" />
							<!-- Adds classes to the menu item -->
							<input type="hidden" class="menu-item-classes" name="menu-item[<?php echo esc_attr( $i ); ?>][menu-item-classes]" value="<?php echo esc_html( $details['class'] ); ?>" />
							<!-- Adds the object type (*not* custom post type but the type which indicates which table it's in) -->
							<input type="hidden" class="menu-item-classes" name="menu-item[<?php echo esc_attr( $i ); ?>][menu-item-object]" value="<?php echo esc_attr( $details['object-type'] ); ?>" />
						</li>
						<?php
						$i--;
						endforeach;
				?>
				</ul>
			</div>
			<p class="button-controls">
				<span class="add-to-menu">
					<button type="submit" class="button-secondary submit-add-to-menu right" value="<?php esc_attr_e( 'Add to menu', 'mjjmenu' ); ?>" name="add-post-type-menu-item" id="submit-mjj-conditional-menu-items"><?php esc_html_e( 'Add to menu', 'mjjmenu' ); ?></button>
					<span class="spinner"></span>
				</span>
			</p>
		</div>
			<?php
	}

	/**
	 * This filters the label on the nav item in the list so it says something other than the default "Custom link" for certain item types.
	 *
	 * @param object $item The nav menu item object.
	 * @return object The nav menu item object.
	 */
	public function nav_type_labels( $item ) {

		$types = $this->mjj_menu_types;

		if ( ! empty( $types[ $item->type ] ) ) {
			$item->type_label = $types[ $item->type ];
		}

		return $item;
	}

	/**
	 * Updates the menu item's url to the correct one.
	 *
	 * @param int   $menu_id The id of the menu.
	 * @param int   $menu_item_db_id The id of the menu item.
	 * @param array $args The values which were saved as postmeta and in the menu item's posts entry.
	 * @return void
	 */
	public function add_back_url( $menu_id, $menu_item_db_id, $args ) {
		$mjj_types = $this->mjj_menu_types;
		$item_type = $args['menu-item-type'];
		if ( ! empty( $mjj_types[ $item_type ] ) ) {
			$object_id = $args['menu-item-object-id'];
			$object    = $args['menu-item-object'];
			$url       = $this->get_link( $object_id, $object ); // Private function which gets the correct link depending on the object type and object id.
			update_post_meta( $menu_item_db_id, '_menu_item_url', esc_url_raw( $url ) );
		}
	}
}