Without Yii3

Every class in the package is a plain PSR component, so you can use it in any PSR-7/PSR-15 application: Mezzio, Slim 4, a custom stack, or Yii3 without yiisoft/config.

Install

composer require crenspire/yii3-inertia:^2.0

You also need a PSR-17 factory implementation, for example nyholm/psr7.

Create the services

use Crenspire\Inertia\Inertia;
use Crenspire\Inertia\Middleware\InertiaMiddleware;
use Crenspire\Inertia\Version\ManifestVersion;
use Crenspire\Inertia\View\PhpRootViewRenderer;
use Crenspire\Inertia\Vite\Vite;
use Nyholm\Psr7\Factory\Psr17Factory;

$factory = new Psr17Factory();

$vite = new Vite(
    publicPath: __DIR__ . '/public',
    devServerUrl: getenv('VITE_DEV_SERVER_URL') ?: null,
);

$inertia = new Inertia(
    responseFactory: $factory,
    streamFactory: $factory,
    rootViewRenderer: new PhpRootViewRenderer(__DIR__ . '/resources/views/inertia.php', ['vite' => $vite]),
    version: new ManifestVersion($vite->getManifestPath()),
    sharedProps: ['appName' => 'My App'],
);

$middleware = new InertiaMiddleware($inertia, $factory);

Register $middleware in your pipeline before routing, and make $inertia available to your request handlers, typically through your container.

Constructor arguments

Argument	Type	Default	Description
responseFactory	ResponseFactoryInterface	required	Creates responses
streamFactory	StreamFactoryInterface	required	Creates response bodies
rootViewRenderer	RootViewRendererInterface	required	Renders the HTML document
version	VersionProviderInterface	new StaticVersion()	Asset version
flashStore	?FlashStoreInterface	null	Storage for flash data across redirects
ssrGateway	?GatewayInterface	null	Server-side rendering
logger	?LoggerInterface	null	Logs rescued deferred props
sharedProps	array	[]	Props shared with every page
encryptHistory	bool	false	History encryption
allErrors	bool	false	Send all validation messages per field

Flash data without yiisoft/session

SessionFlashStore requires yiisoft/session. With another session library, implement FlashStoreInterface. For PHP's native session:

use Crenspire\Inertia\Flash\FlashStoreInterface;

final class NativeSessionFlashStore implements FlashStoreInterface
{
    public function set(string $key, mixed $value): void
    {
        $_SESSION[$key] = $value;
    }

    public function get(string $key): mixed
    {
        return $_SESSION[$key] ?? null;
    }

    public function pull(string $key): mixed
    {
        $value = $_SESSION[$key] ?? null;
        unset($_SESSION[$key]);

        return $value;
    }
}

Pass it as flashStore to Inertia, and to new InertiaFlash($store) to write errors and data.

Complete example

examples/psr15 is a runnable application with a router, a form with validation, deferred props and flash messages, built only from PSR components.