JSON API action: WebViewRenderer::render('') throws 'The view path is not set'

JSON API action: WebViewRenderer::render('') throws "The view path is not set"

Description

When building a JSON API endpoint in a Yii3 yiisoft/app project, the most intuitive approach is to reuse WebViewRenderer and return an empty view with a JSON body, e.g.:

final readonly class HealthAction
{
    public function __construct(private WebViewRenderer $viewRenderer) {}

    public function __invoke(): ResponseInterface
    {
        $response = $this->viewRenderer->render('')
            ->withHeader('Content-Type', 'application/json');
        $response->getBody()->write(json_encode([...]));
        return $response;
    }
}

This throws:

LogicException: The view path is not set.
vendor/yiisoft/yii-view-renderer/src/WebViewRenderer.php:101

Environment

• yiisoft/app (latest stable, composer create-project 2026-08)
• PHP 8.3.30, current yiisoft/yii-view-renderer

Workaround that works

Use Psr\Http\Message\ResponseFactoryInterface (already bound in config/web/di/psr17.php) to build the JSON response directly instead of WebViewRenderer.

Questions for maintainers

1. Is WebViewRenderer::render('') intended to be usable for non-HTML responses, or should the docs/examples explicitly recommend ResponseFactoryInterface for JSON APIs?
2. If the former, is "The view path is not set" the expected behaviour, or should an empty/raw response path be allowed for API actions?

A minimal reproducible example is attached (Vanilla JS + Yii3 co-work demo, see linked PR/discussion).

Start at vendor/yiisoft/yii-view-renderer/src/WebViewRenderer.php:101 and review config/web/di/psr17.php, which already binds ResponseFactoryInterface. Clarify whether the intended outcome is renderer support or documentation recommending the response factory; done requires a maintainer decision and corresponding behavior or guidance, with validation for the JSON API case.