middleware-server-request-trait.php

trait RequiresServerRequestTrait
{
  /** 
   * @param RequestInterface $request
   * @return ServerRequestInterface
   * @throws ServerRequestRequiredException
   */
  private function ensureServerRequest(RequestInterface $request)
  {
      if (($request instanceof ServerRequestInterface) === false) {
          throw ServerRequestRequiredException::requiredBy($this);
      }
      return $request; // add this line
  }
}


class ExampleMiddleware
{
    use RequiresServerRequestTrait;
    public function __invoke(
        RequestInterface $request,
        ResponseInterface $response,
        callable $next
    ) {
        $serverRequest = $this->ensureServerRequest($request);
        // ...
    }
}