Building a Custom WordPress Navigation Menu Plugin

This is a semi-advanced WordPress tutorial so you should have a little bit of existing knowledge of WordPress if you want to be able to understand the concepts involved. I will try to make it as easy to follow as possible none-the-less.

We are just going to dive right in a create a new Plugin. I'll be calling the plugin Jafty-Nav, you can follow suit if you wish to keep things simple or give it your own name if you feel comfortable making such changes.

Create a New Plugin

<?php
/**
* Plugin Name: Jafty Top Nav Plugin
* Plugin URI: http://jafty.com/blog/?p=9813
* Description: A Plugin that adds a custom top navigation menu to WordPress.
* Version: 1.0
* Author: Ian L. of Jafty.com
* Author URI: http://jafty.com
* License: GPL2
*/

Register a New Menu Location with WordPress

Add this PHP code to your plugin file you created above:

<?php
add_action('after_setup_theme', 'register_jafty_menu');
function register_jafty_menu(){
  register_nav_menu('jafty-top-nav', __('Primary Jafty Menu', 'jafty-top-nav-plugin'));
}
?>

Now that is actually enough to create a simple plugin. The plugin will add a menu location to wp-admin and that's it, but we'll build on it after we install it. So go ahead and install the plugin by putting it into a folder named "jafty-top-nav-plugin" and naming the file "index.php". Then upload to your WordPress plugins directory. Activate the Jafty Top Nav Plugin then go to your admin and click on "Appearance/Menus" then select the "Manage Locations" tab and you'll see the new menu location your plugin as added to the admin like in the image below.

menuLOC

Placing a new top nav in your theme

The next task is to edit your current WordPress theme to work with the Jafty Top Nav Plugin. You'll need to create a new header file and edit your page, post and/or home page templates to contain your new top navigation menu. Here is how:

  1. Go into your current theme's folder and download a copy of the header.php file to your desktop and rename it header-jafty.php.
  2. open header-jafty.php in notepad and find the section that looks something like this:<nav id="site-navigation" class="main-navigation" role="navigation">
    <button class="menu-toggle" aria-controls="primary-menu" aria-expanded="false"><?php esc_html_e( 'Primary Menu', 'outer-gain-dev' ); ?></button>
    <?php wp_nav_menu( array( 'theme_location' => 'menu-1', 'menu_id' => 'primary-menu' ) ); ?>
    </nav>
  3. Inside the code within the Nav tag in your header-jafty.php file, change the theme_location value to 'jafty-top-nav' and save the file.
  4. Now upload your header-jafty.php file to your active theme's folder.
  5. Next you'll want to add the new header to your template files, Some templates you might want to do this too are front-page.php, single.php, page.php and any custom page templates in your theme or child theme you might have. The process is very similar for adding the new header to any of the files, so I'll just demonstrate on the home page template file, front-page.php. Open the template file in your notepad and near the top of the code you should see something like this:
    get_header();
    or you may have something like this instead:
    get_template_part('templates/header.php');
    Regardless which you have, replace the line with:
    get_header('jafty');
    and that will call your new header.jafty.php template into the page template so your customized header will be shown.
  6. Save and upload your altered template file and repeat for all necessary page and post templates until you have your new top nav menu at the top of all desired pages and/or posts throughout your entire WordPress site.

Now that we have more control of it, let's customize that ugly top nav!

Customizing the WP Navigation Menu

It's time to get down and dirty with some real-world customization of the top navigation menu in WordPress. We are not just doing some simple CSS changes here, we are talking about a complete rewrite of the navigation system. This is why I went with a plugin for this. Now I had to find what WordPress core functions I could use to alter the menu completely. My goal is to make a menu similar to the one at Stripe.com, which is not a WordPress site by the way. I just love the dynamic drop downs that fade in and out and their use of icons in the sub-menu items. I'll get to how I duplicated all of that later on, first we need to know how to rebuild the entire menu structure because the stripe.com style menu is nothing like a standard WordPress menu. Here's what I figured out:

 

First we need to be able to retrieve our custom navigation links from the WordPress backend. Remember earlier we created a menu location? Well, we need to retrieve the menu assigned to that particular location in WordPress. Therefore the first thing we want to do is make sure there is a menu assigned to the "Primary Jafty Menu". You could pick one from the drop down, but we want to make a new one that is sure to have both main menu items and sub menu items so we can adequately test our menu when it's complete. Therefore we locate the "Primary Jafty Menu" and click the link to the right of it that reads "Use New Menu" as I've circled in red in the below image:

menuLOC2

When creating the new Primary Jafty Menu, give it a name of "Jafty 1". It's best to do everything exactly as I have done just to be sure you don't have any conflicts. You can always change names and such after you have a completed working plugin. When creating the menu, make sure to add at least 2 main menu items with at least 2 sub menu items each so we can test the drop down effects. Here is an image of the one I made for testing. If you don't have enough pages or posts to make that many links, don't worry, just use two real links for the main menu items and click on "custom links" and create outside links for all of your sub menu items as I have done in the below image:

menustructure

In the above image, "site settings" and "Hello world!" represent our two main menu items and the sub links rest below them indented to show their sub-link status. Notice I have "Primary Jafty Menu" checked under "Menu Setings" too. Once you have your menu, be sure you save it. Now we can return to developing our plugin!

Retrieve Menu and Sub Menu Items from WordPress Admin

It is time to develop some custom WordPress code to extract out menu items and sub-menu items from the database. Lucky for us, WordPress has some built-in core functions to assist us. Here is the code I come up with to extract all menu and sub-menu items for the "Jafty Primary Menu" from the database to display them on the front-end:

<?php
      $menuLocations = get_nav_menu_locations(); // Get nav locations
      $menuID = $menuLocations['jafty-top-nav']; //menu assigned to Jafty Primary Menu
      $theNav = wp_get_nav_menu_items($menuID);
                
                    foreach ($theNav as $navItem) {
                        //get the url for the link:
                        $navURL = $navItem->url;
                        //get the nav link text/title:
                        $navTXT = $navItem->title;
                        //Get the nav link's ID:
                        $navID = $navItem->ID;
                        //Get menu item parent(will be 0 if main link or parent ID if it's a sub link):
                        $navParent  = $navItem->menu_item_parent;
                        echo "ID: $navID, $navTXT, $navParent, $navURL<br />";
                    //echo '<li class="has-dropdown gallery" data-content="about"><a href="'.$navURL.'" title="'.$navItem->title.'">'.$navTXT.'</a></li>';
                    }
 ?>

The above code will go in out header file named header-jafty.php. Lets examine the code so you understand what it does.

The first line:

$menuLocations = get_nav_menu_locations(); // Get nav locations

as the comment says afterwards, it gets the navigation menu locations stored in WordPress. We added one of these in the beginning of the tutorial using the register_nav_menu function.

The second line reads:

$menuID = $menuLocations['jafty-top-nav']; //menu assigned to 'Primary Jafty Menu'

This line fetches the ID of the menu currently assigned to the menu location we created in the plugin file, "Primary Jafty Menu". We then use the id in the next line that reads:

$theNav = wp_get_nav_menu_items($menuID);

We now have a WordPress menu object stored in $theNav. If you do a print_r($theNav) command in PHP, you would see that the menu object holds all sorts of information about the menu we created earlier. However, we only need four key pieces of information from the menu object. We need to get:

  1. The Link URL
  2. The Link Text
  3. The Link ID
  4. The Link's Parent ID in case it is a sub-menu item.

We can get the four pieces of information we need using a foreach loop on the $theNav object like so:

     foreach ($theNav as $navItem) {
                        //get the url for the link:
                        $navURL = $navItem->url;
                        //get the nav link text/title:
                        $navTXT = $navItem->title;
                        //Get the nav link's ID:
                        $navID = $navItem->ID;
                        //Get menu item parent(will be 0 if main link or parent ID if it's a sub link):
                        $navParent  = $navItem->menu_item_parent;
                        echo "ID: $navID, $navTXT, $navParent, $navURL<br />";
                    //echo '<li class="has-dropdown gallery" data-content="about"><a href="'.$navURL.'" title="'.$navItem->title.'">'.$navTXT.'</a></li>';
                    }

We now have all the information we need about the menu items after running the above foreach loop on the menu object. We have the link text, URL, ID and Parent ID. It's important to note that the parent ID will always be 0 if the link is a main menu item and we can determine if the link is a sub-menu item if the parent ID is anything other than zero. Then we know which link to put the sub-link under by matching the sub-link's parent ID to the ID of the main link item. Pretty simply really, once you get accustomed to it.

Now we need to open our header-jafty.php file and find the line that reads something similar to:

<?php wp_nav_menu( array( 'theme_location' => 'jafty-top-nav', 'menu_id' => 'primary-menu' ) ); ?>

And replace it with the code we wrote above:

<?php
$menuLocations = get_nav_menu_locations(); // Get nav locations
$menuID = $menuLocations['jafty-top-nav']; // Get the *primary* menu ID
$theNav = wp_get_nav_menu_items($menuID);

foreach ($theNav as $navItem) {
//get the url for the link:
$navURL = $navItem->url;
//get the nav link text/title:
$navTXT = $navItem->title;
//Get the nav link's ID:
$navID = $navItem->ID;
//Get menu item parent(will be 0 if main link or parent ID if it's a sub link):
$navParent  = $navItem->menu_item_parent;
echo "ID: $navID, $navTXT, $navParent, $navURL<br />";
//echo '<li class="has-dropdown gallery" data-content="about"><a href="'.$navURL.'" title="'.$navItem->title.'">'.$navTXT.'</a></li>';
}
?>

Now save your header-jafty.php file and upload it to your active theme's folder and refresh your home page. You should see the following information printed in the header area of your site instead of a top nav now:

ID: 47, Site Settings, 0, http://dev.outergain.com/site-settings/
ID: 49, Jafty Interactive, 47, http://jafty.com
ID: 50, Jafty Blog, 47, http://jafty.com/blog
ID: 48, Hello world!, 0, http://dev.outergain.com/2016/12/30/hello-world/
ID: 51, Yahoo Search, 48, http://yahoo.com
ID: 52, Google Search, 48, http://google.com

As you can see my site returned 6 lines of text in the header, one for each of the two main menu items and one for each of the four sub-menu items in the menu I created in wp-admin. Each of the lines above contains the main ID first, followed by the link text, then the parent ID and finally the link text. I highlighted the parent IDs in blue so you can see how the two main menu items have a parent ID of zero while the other four have parent IDs equal to the two main menu items with zero for parent ID. Make sense? I hope so:-)

For all you professional WordPress plugin developers, I can probably stop there. Now you have enough to make your own custom top navigation menu for your WordPress theme. You clearly don't need to do this as a plugin, in fact, it would normally done by adding the plugin code to functions.php in the current theme instead. I am making it a plugin just as a learning exercise.

You can use the information it printed in your header to figure out how to add in the HTML and CSS for any type of custom nav you desire, or you can read on to see how I recreated the stripe.com-like top nav for one of my clients.

Make a Static Top Navigation Menu as a Demo

Before we go about coding the menu into WordPress, I like to create a static version first. I created mine based on looking at the top nav found on Stripe.com. You can click the link to see what I mean. I didn't copy it by any means, but I did use it as a model for creating a similar one with similar transition effects. In the static demo, I didn't create great detail in the drop downs. Instead I concentrated on getting the transition effects and infrastructure perfect. I can worry about making the content of the dropdown boxes look pretty when I code it into the actual WordPress site. Here is my static demo: http://jafty.com/nav_demo

I won't post all of the code to my static navigation menu demo here but you may feel free to use the link provided and use your browser's view source option to see how I made it and copy it if you so desire.

 

 

 

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