UserController.php

<?php

// ...

class UserController extends AbstractApiController
{   
    /**
     *
     * @Rest\View()
     * @Rest\QueryParam(name="_token", description="The token for authentication.")
     * @ApiDoc(
     *  resource=true,
     *  description="Gets User associated to id. Needs Authentication.",
     *  statusCodes={
     *      200="Returned when successful",
     *      400="Returned when the token is invalid.",
     *      403="Returned when the enquirer is not authorized."
     *  },
     *  filters={
     *      {"name"="_format", "dataType"="string", "pattern"="(json|xml)"}
     *  }
     * )
     */
    public function getUserAction(ParamFetcherInterface $paramFetcher, $id)
    {   
        $manager    = $this->getDoctrine()->getManager();
        $repository = $manager->getRepository('WildlyCoreBundle:User');

        if(null === ($token = $paramFetcher->get('_token'))) {
            throw new HttpException(400, 'Missing authentication token.');
        }
        if(null === ($enquirer = $repository->findOneByApiToken($token))) {
            throw new HttpException(400, 'Invalid authentication token.');
        }   
        if(false === $enquirer->getIsActive()) {
            throw new HttpException(403, 'Forbidden. User with request token is disabled.');
        }

        // @todo load user
        $user = null;

        return $user;  
    }
}