颤振-自更新到firebase 9.0.X以来的错误event.snapshot.value

Question

自从更新到firebase 9.0.5之后，我在event.snapshot.value上得到了错误。我有许多像这样的函数，在firebase 8.X中工作得很好。

  Stream<List<MentorModel>> mentorStream() {
    final stream = _database.onValue;

    final Stream<List<MentorModel>> resultStream = stream.map((event) {
      List<MentorModel> _mentorList = [];
      Map<String, dynamic>.from(event.snapshot.value).forEach((key, value) => _mentorList.add(MentorModel.fromRTDB(key, value)));
      return _mentorList;
    });

    return resultStream;
  }

现在我在event.snapshot.value上有了错误标记，android说

Error: The argument type 'Object?' can't be assigned to the parameter type 'Map<dynamic, dynamic>'.
 - 'Object' is from 'dart:core'.
 - 'Map' is from 'dart:core'.
      Map<String, dynamic>.from(event.snapshot.value).forEach((key, value) => _mentorList.add(MentorModel.fromRTDB(key, value)));

当我尝试

Map<String, dynamic>.from(event.snapshot.value as Map<String, dynamic>).forEach((key, value) => 

然后错误标记就消失了，但是当我运行应用程序时，它会返回

E/flutter (16737): [ERROR:flutter/shell/common/shell.cc(93)] Dart Unhandled Exception: type '_InternalLinkedHashMap<Object?, Object?>' is not a subtype of type 'Map<String, dynamic>' in type cast, stack trace: 

火柴9.0到底发生了什么变化？如何在FireBase9.0中迭代event.snapshot.value？

Answer 1

从Firebase v9，他们从使用dynamic转移到Object?，开始将Object?转换为Map可能会很麻烦，因为experienced..Simply使对象dynamic可以消除麻烦。

尝试：

Map<String, dynamic>.from(event.snapshot.value as dynamic).forEach((key, value) => _mentorList.add(MentorModel.fromRTDB(key, value)));

Answer 2

‘statut: json'statut’!= null？(json‘’statut‘作为列表).map((I) => Statut.fromJson(Map.from(作为动态的)).toList()：null，