README

Inertia.js server-side adapter for PHP — the equivalent of what inertia-laravel provides on Laravel, for any plain-PHP application.

It is framework-agnostic: everything runs on native PHP. When WordPress is loaded, its helpers (wp_json_encode, status_header, sanitize_text_field, wp_head / wp_footer in the default shell, the blog_charset option, …) are picked up automatically — no configuration needed.

It handles the full Inertia protocol:

• First / standard visit → full HTML document with the page object embedded in a JSON script tag (script[data-page="<id>"][type="application/json"], the Inertia v3 convention).
• Inertia visit (XHR with X-Inertia: true) → bare JSON page object, no HTML, so the client swaps props without a page reload.
• Stale assets (X-Inertia-Version mismatch on GET) → 409 + X-Inertia-Location, telling the client to do one hard reload to pick up new bundles.
• Partial reloads → prop filtering via X-Inertia-Partial-Data / X-Inertia-Partial-Except, with closure props resolved lazily after filtering so skipped props cost no queries.

Installation

composer require webkul/inertia

While the package lives inside a project as a path repository, add to the project's composer.json:

{
    "repositories": [
        { "type": "path", "url": "packages/inertia" }
    ],
    "require": {
        "webkul/inertia": "@dev"
    }
}

Usage

Plain PHP

use Webkul\Inertia\Inertia;

$inertia = Inertia::instance()
    ->set_version( '1.0.0' )   // string or callable, e.g. a build hash
    ->set_app_id( 'app' );     // container / script id for the default shell

$inertia->render( 'Order', array(
    'orders'  => fn() => fetch_orders(), // lazy: skipped on partial reloads
    'filters' => $filters,
) );

WordPress (custom HTML shell)

use Webkul\Inertia\Inertia;

$inertia = Inertia::instance()
    ->set_version( MY_PLUGIN_SCRIPT_VERSION )
    ->set_root_view( array( My_Template::instance(), 'render_ui_template' ) );

if ( ! $inertia->is_inertia_request() ) {
    // Assets are only needed for the HTML shell, not for JSON visits.
    my_plugin_enqueue_app_assets();
}

$inertia->render( 'Order', $props );

render() always terminates the request.

Configuration

If no root view is configured, a minimal shell is rendered: a JSON script tag plus an empty <div id="<app id>"> — and, inside WordPress, wp_head() / wp_footer() / body_class() are included automatically.

Examples

Runnable end-to-end examples live in examples/:

• examples/react/ — client built with the official @inertiajs/react adapter (React 18), including SPA links and partial reloads via router.reload({ only: [...] }).
• examples/vanilla-js/ — no framework: a ~70 line hand-rolled client showing the raw protocol (boot from the JSON script tag, fetch() visits with X-Inertia headers, the 409 hard-reload handshake, partial reloads, back/forward handling).

Each folder is a standalone mini-app: php -S localhost:8000 index.php.