Question

我正在尝试将文档添加到我的Cloud Firestore数据库中。以这种方式。

Future<String> currentlyIn()async{
     FirebaseAuth auth = FirebaseAuth.instance;
    String fuser = await auth.currentUser();
    });
     return fuser.uid;
   }


Map<String, dynamic> votedown() {
    Map<String, dynamic> comdata = <String, dynamic>{
      'user_Id':currentlyIn(),
      'actual_vote':0,
      'voteUp': false,

    };
    return comdata;
  }

DocumentReference storeReference =Firestore.instance.collection('htOne').document('docq');
  await storeReference.setData(votedown());

但是，无论何时我运行代码，都会出现此错误。我需要有关如何成功解决此问题的帮助

E/flutter ( 6263): [ERROR:flutter/shell/common/shell.cc(181)] Dart Error: Unhandled exception: 
E/flutter ( 6263): Invalid argument: Instance of 'Future<String>'
E/flutter ( 6263): #0      StandardMessageCodec.writeValue (package:flutter/src/services/message_codecs.dart:353:7) 
E/flutter ( 6263): #1      FirestoreMessageCodec.writeValue (file:///C:/NoFlutterPerms/Git/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.7.4/lib/src/firestore_message_codec.dart:38:13)

Answer 1

currentlyIn返回一个Future。您需要这样对待它。期货不会自动转换为其完成的价值。

您可以像这样使用async / await：

Future<Map<String, dynamic>> votedown() async {
    Map<String, dynamic> comdata = <String, dynamic>{
      'user_Id': await currentlyIn(),
      'actual_vote':0,
      'voteUp': false,

    };
    return comdata;
  }

DocumentReference storeReference =Firestore.instance.collection('htOne').document('docq');
  await storeReference.setData(await votedown());

Answer 2

您正试图将Future<String>对象用作String，因此它给出了错误。请尝试以下代码。

  currentlyIn().then((value){
   Map<String, dynamic> comdata = <String, dynamic>{
  'user_Id': value,
  'actual_vote':0,
  'voteUp': false,
   };

  return comdata;
  });

Dart错误：未处理的异常：E / flutter（5079）：无效的参数：'Future <string>'的实例

2 个答案: