我是Flutter的新手。我正在尝试用API执行插入操作。在执行此操作时，我想获取当前日期并用api保存它。但是我得到了错误。我如何才能尽快解决它呢？以下是我的代码

var myinsert={"ID":sayac,"MAS_ID":1,"PALET_NO":e.PALETNO,"TARIH":DateTime.now(),"HUCRE_KODU":e.HUCREKODU,"MIKTAR":e.MIKTAR,"HAREKET_TIPI":"PALET TOPLAMA"};
    String uri = 'http://192.168.0.21/api/values/DegerEkle/';
    Uri ur = Uri.parse(uri);

    final response = await http.post(ur, headers: {
      'Content-Type': 'application/json'
    },
    body: jsonEncode(myinsert))
    .timeout(const Duration(seconds: 30));
    print(response);

以下是我的错误消息

Exception has occurred.
JsonUnsupportedObjectError (Converting object to an encodable object failed: Instance of 'DateTime')