Question

我想使用mongo存储我的应用数据，但是当我尝试await db.open()时，控制台上会出现此错误：

[ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (11408): type 'Future<dynamic>' is not a subtype of type 'Future<bool>' where
E/flutter (11408):   Future is from dart:async
E/flutter (11408):   Future is from dart:async
E/flutter (11408):   bool is from dart:core
E/flutter (11408):
E/flutter (11408): #0      _Connection.connect (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/network/connection.dart:73:22)
E/flutter (11408): #1      _ConnectionManager._connect (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/network/connection_manager.dart:23:22)
E/flutter (11408): <asynchronous suspension>
E/flutter (11408): #2      _ConnectionManager.open.<anonymous closure> (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/network/connection_manager.dart:58:14)
E/flutter (11408): #3      Future.forEach.<anonymous closure> (dart:async/future.dart:484:26)
E/flutter (11408): #4      Future.doWhile.<anonymous closure> (dart:async/future.dart:526:26)
E/flutter (11408): #5      _RootZone.runUnaryGuarded (dart:async/zone.dart:1316:10)
E/flutter (11408): #6      _RootZone.bindUnaryCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1355:26)
E/flutter (11408): #7      Future.doWhile (dart:async/future.dart:541:18)
E/flutter (11408): #8      Future.forEach (dart:async/future.dart:482:12)
E/flutter (11408): #9      _ConnectionManager.open (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/network/connection_manager.dart:56:19)
E/flutter (11408): #10     Db.open.<anonymous closure> (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/database/db.dart:252:33)
E/flutter (11408): #11     new Future.sync (dart:async/future.dart:222:31)
E/flutter (11408): #12     Db.open (file:///C:/Users/Picmix/flutter/.pub-cache/hosted/pub.dartlang.org/mongo_dart-0.3.1/lib/src/database/db.dart:239:16)
E/flutter (11408): #13     main (file:///F:/Jamil/WORKSHOP/MY-PRACTICE/FLUTTER/FLUTTERMONGO/simplecrud/lib/main.dart:6:6)
E/flutter (11408): <asynchronous suspension>
E/flutter (11408): #14     _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:279:19)
E/flutter (11408): #15     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)
E/flutter (11408): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (11408): type '(MongoReplyMessage) => void' is not a subtype of type '(dynamic) => void'
E/flutter (11408): #0      _rootHandleUncaughtError.<anonymous closure> (dart:async/zone.dart:1114:29)
E/flutter (11408): #1      _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter (11408): #2      _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)

这是我写的用于在mlab和app之间打开连接的简单代码：

import 'package:mongo_dart/mongo_dart.dart';

void main() async {
  print('hello');
  Db db = new Db('mongodb://<myusername><mypassword>@ds147659.mlab.com:47659/simple-crud');
  db.open().then((success) {
    if (success) print('connected');
  });
}

任何想法，先生？

Answer 1

这是由于最新的扑克更新beta2。请查看此blog by flutter

看起来你的项目和Mongo插件的版本不匹配。

Mongo的最新插件于2017年10月24日更新。

已有issue on their git。你可以跟踪它。

同时，根据this issue：您可以尝试从

更改插件代码

Future<bool> get isOn => _channel.invokeMethod('isOn');

到

Future<bool> get isOn async {
 final bool isOn = await _channel.invokeMethod('isOn');
 return isOn;
}

注意：以上只是一个示例，请检查插件dart文件以获取正确的更改功能。

颤动：Mongo Dart插件不起作用

1 个答案: