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Inertia.js WordPress Adapter

The unofficial Inertia.js server-side adapter for WordPress.

Installation

Option 1: Install the package via composer. (Recommended)

composer require boxybird/inertia-wordpress

Option 2: Clone or download as a plugin and run composer install before activating in WordPress Admin.

Bare-bones Example Theme

Example Movie CPT WordPress Project

Inertia Docs

Root Template Example

Location: /wp-content/themes/your-theme/app.php

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <?php wp_head(); ?>
    </head>
    <body>

        <?php bb_inject_inertia(); ?> // Adds Inertia to the page

        <?php wp_footer(); ?>
    </body>
</html>

Root Template File Override

Location: /wp-content/themes/your-theme/functions.php

By default the WordPress adapter will use the app.php from .../your-theme/app.php. If you would like to use a different file name, you can change it. E.g. .../your-theme/layout.php.

<?php

add_action('init', function () {
    Inertia::setRootView('layout.php');
});

Inertia Function Output Override

By default the bb_inject_inertia() function returns <div id="app" data-page="{...inertiaJsonData}"></div>. If you need to override the div id, you can.

// Override 'id="app"' to 'id="my_app"' and add classes
<?php bb_inject_inertia('my_app', 'bg-blue-100 font-mono p-4'); ?>

Inertia Response Examples

Basic

Location: /wp-content/themes/your-theme/index.php

<?php

use BoxyBird\Inertia\Inertia;

global $wp_query;

Inertia::render('Index', [
    'posts' => $wp_query->posts,
]);

Less Basic

Location: /wp-content/themes/your-theme/index.php

This may look busy, however it can be thought of as a "Controller". It gives you a place to handle all your business logic. Leaving your Javacript files easier to reason about.

<?php

use BoxyBird\Inertia\Inertia;

global $wp_query;

// Build $posts array
$posts = array_map(function ($post) {
    return [
        'id'      => $post->ID,
        'title'   => get_the_title($post->ID),
        'link'    => get_the_permalink($post->ID),
        'image'   => get_the_post_thumbnail_url($post->ID),
        'content' => apply_filters('the_content', get_the_content(null, false, $post->ID)),
    ];
}, $wp_query->posts);

// Build $pagination array
$current_page = isset($wp_query->query['paged']) ? (int) $wp_query->query['paged'] : 1;
$prev_page    = $current_page > 1 ? $current_page - 1 : false;
$next_page    = $current_page + 1;

$pagination = [
    'prev_page'    => $prev_page,
    'next_page'    => $next_page,
    'current_page' => $current_page,
    'total_pages'  => $wp_query->max_num_pages,
    'total_posts'  => (int) $wp_query->found_posts,
];

// Return Inertia view with data
Inertia::render('Posts/Index', [
    'posts'      => $posts,
    'pagination' => $pagination,
]);

Quick Note

You may be wondering what this moster line above does:

'content' => apply_filters('the_content', get_the_content(null, false, $post->ID));

Because we can't use the WordPress function the_content() outside of a traditional theme template setup, we need to use get_the_content() instead. However, we first need to apply the filters other plugins and WordPress have registered.

Matter of fact, we can't use any WordPress function that uses echo, and not return.

But don't fret. WordPress typically offers a solution to this caveat: get_the_title() vs the_title(), get_the_ID() vs the_ID(), and so on...

Reference: https://developer.wordpress.org/reference/functions/

Shared data

Location: /wp-content/themes/your-theme/functions.php

add_action('init', function () {
    // Synchronously using key/value
    Inertia::share('site_name', get_bloginfo('name'));

    // Synchronously using array
    Inertia::share([
        'primary_menu' => array_map(function ($menu_item) {
            return [
                'id'   => $menu_item->ID,
                'link' => $menu_item->url,
                'name' => $menu_item->title,
            ];
        }, wp_get_nav_menu_items('Primary Menu'))
    ]);

    // Lazily using key/callback
    Inertia::share('auth', function () {
        if (is_user_logged_in()) {
            return [
                'user' => wp_get_current_user()
            ];
        }
    });

    // Lazily on partial reloads
    Inertia::share('auth', Inertia::lazy(function () {
        if (is_user_logged_in()) {
            return [
                'user' => wp_get_current_user()
            ];
        }
    }));

    // Multiple values
    Inertia::share([
        // Synchronously
        'site' => [
            'name'       => get_bloginfo('name'),
            'description'=> get_bloginfo('description'),
        ],
        // Lazily
        'auth' => function () {
            if (is_user_logged_in()) {
                return [
                    'user' => wp_get_current_user()
                ];
            }
        }
    ]);
});

Asset Versioning

Location: /wp-content/themes/your-theme/functions.php

Optional, but helps with cache busting.

add_action('init', function () {
    // If you're using Laravel Mix, you can
    // use the mix-manifest.json for this.
    $version = md5_file(get_stylesheet_directory() . '/mix-manifest.json');

    Inertia::version($version);
});