var loginInfo = await KdApi.login("http://Your Server IP", "60d19671dd1820", "account", "password");
if (!loginInfo.isLoginSuccess) {
    debugPrint("login failure!");
    return;
}

var resp = await KdApi.query(formId: "SAL_SALEORDER", fieldKeys: ["FBillNo", "FCustId"]);
debugPrint(resp.toString());