function checkUniqueEmail($email_str)
    {

        $user = new UsuarioModel();
        $result = $user->findOne(array ('email_str' => '$email_str'));

        if($result != NULL){
            return true;
        }
        return false;
    }

    function  retornarPreferencias($email_str){
        $user= new UsuarioModel();
        $result = $user->find(array ('email_str' => $email_str));


        return $result.$user->preferencias_arr;

    }

    function getUsuario($email_str){
        $user= new UsuarioModel();
        $result = $user->find(array ('email_str' => $email_str));

        return $result.$user;
    }