SQLSTATE[HY000] [2002] No such file or directory

class Config {
    const dbhost = 'localhost';
    const dbname = 'dbbanco';
    const dbuser = 'dbsenha';
    const dbpass = 'dbusuario';
}

class Connection extends Config {
    private $dbhost = parent::dbhost;
    private $dbname = parent::dbname;
    private $dbuser = parent::dbuser;
    private $dbpass = parent::dbpass;
    private $dbconn = null;

    function __construct() {
        if (empty($this->dbconn)) {
            $dbparams = array(
                'dbhost' => $this->dbhost,
                'dbname' => $this->dbname,
                'dbuser' => $this->dbuser,
                'dbpass' => $this->dbpass
            );
            return $this->dbconn = $this->dbConnect($dbparams);
        }
    }

    private function dbConnect(array $dbparams) {
        if (!empty($dbparams['dbhost']) && !empty($dbparams['dbname']) && !empty($dbparams['dbuser']) && !empty($dbparams['dbpass'])) {
            $dbopts = array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8", PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            try {
                $this->dbconn = new PDO("mysql:dbhost=" . $dbparams['dbhost'] . ";dbname=" . $dbparams['dbname'] . "", $dbparams['dbuser'], $dbparams['dbpass'], $dbopts);
                return $this->dbconn;
            } catch (PDOException $error) {
                exit('<h1>Falha na conexão com o banco de dados.</h1><h2>Detalhes da falha:</h2><pre>' . $error->getMessage() . '</pre>');
            }
        }
    }

    public function sqlQuery($query = null, $fetch = false, $fetchAll = false) {
        if (!empty($query)) {
            if ($fetch == true) {
                if ($fetchAll == true) {
                    $this->dbconn = $this->dbconn->query($query);
                    return $this->dbconn->fetchAll();
                } else {
                    $this->dbconn = $this->dbconn->query($query);
                    return $this->dbconn->fetch(PDO::FETCH_ASSOC);
                }
            } else {
                return $this->dbconn->query($query);
            }
        } else {
            return 'Nenhuma consulta SQL foi informada. Acesso ao banco de dados cancelado.';
        }
    }
}