Firebase 身份验证和数据库规则

我是 Flutter/Dart 的新手，但我一直在努力为我正在从事的项目找出数据库规则。我知道关于 Firebase DB 规则的 SO 上有很多帖子，但我发现和尝试的所有内容都没有奏效。在下面的特定情况下，我希望任何人都能够读取数据，但只有作者能够编写和编辑数据。我将 Doc ID 设置为 uid 并且在删除权限的情况下可以正常工作，但是当我添加受限规则时我无法获得任何工作。我究竟做错了什么？

堆栈跟踪消息

I/flutter (17900): PlatformException(Error performing setData, PERMISSION_DENIED: Missing or insufficient permissions., null)
E/flutter (17900): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: setState() called after dispose(): _RegisterState#1360e(lifecycle state: defunct, not mounted)

我的 Firebase 规则：

service cloud.firestore {
  match /databases/{database}/documents {
    match /brews/{userId} {
      allow read: if request.auth.uid != null;
      allow write: if request.auth.uid == userId;
    }
  }
}

数据库代码

class DatabaseService {
  final String uid;
  DatabaseService({this.uid});

  //Collection reference
  final CollectionReference brewCollection =
      Firestore.instance.collection('brews');

  Future updateUserData(String sugars, String name, int strength) async {
    return await brewCollection.document(uid).setData({
      'sugars': sugars,
      'name': name,
      'strength': strength,
    });
  }

  //brew list from snapshot
  List<Brew> _brewListFromSnapshot(QuerySnapshot snapshot) {
    return snapshot.documents.map((doc) {
      return Brew(
        name: doc.data['name'] ?? '',
        strength: doc.data['strength'] ?? 0,
        sugars: doc.data['sugars'] ?? '0',
      );
    }).toList();
  }

  //userData from snapshot
  UserData _userDataFromSnapshot(DocumentSnapshot snapshot) {
    return UserData(
      uid: uid,
      name: snapshot.data['name'],
      sugars: snapshot.data['sugars'],
      strength: snapshot.data['strength'],
    );
  }

  //Get the collection stream
  Stream<List<Brew>> get brews {
    return brewCollection.snapshots().map(_brewListFromSnapshot);
  }

  //get user doc stream
  Stream<UserData> get userData {
    return brewCollection.document(uid).snapshots().map(_userDataFromSnapshot);
  }
}

验证码：

class Authenticate extends StatefulWidget {
  @override
  _AuthenticateState createState() => _AuthenticateState();
}

class _AuthenticateState extends State<Authenticate> {
  bool showSignIn = true;
  void toggleView() {
    setState(() {
      showSignIn = !showSignIn;
    });
  }

  @override
  Widget build(BuildContext context) {
    if (showSignIn) {
      return SignIn(toggleView: toggleView);
    } else {
      return Register(toggleView: toggleView);
    }
  }
}