Check whether parameter exists or not in the request

I have this function:

/**
 * @Secure(roles="IS_AUTHENTICATED_FULLY")
 * @Route("/chequearFabricanteDistribuidor", name="chequearFabricanteDistribuidor", condition="request.headers.get('X-Requested-With') == 'XMLHttpRequest'")
 * @Method("GET")
 */

public function chequearFabricanteAction(Request $request)
{
    $em       = $this->getDoctrine()->getManager();
    $entities = $em->getRepository('AppBundle:FabricanteDistribuidor')->findOneBy(
        array( 'nombre' => $request->query->get('fabricante')['nombre'] )
    );

    $response['valid'] = true;

    if ($entities) {
        $response['valid'] = false;
    }

    return new JsonResponse($response);
}

The function needs to be called from two different forms and the only different is the request var that holds the value. In the first form is: $request->query->get('fabricante')['nombre'] while in the second is $request->query->get('distribuidor')['nombre'] so I'm asking if the right way to handle this could be:

if (isset($request->query->get('fabricante'))) 
{
   $nombre = $request->query->get('fabricante')['nombre'];
}
else
{
   $nombre = $request->query->get('distribuidor')['nombre'];
}

Is this right? Exists a better one?

As Cerad posted on the responses, you could use:

$request->query->has('distribuidor')