Flutter Firestore with Streams getting type '_JsonQueryDocumentSnapshot' is not a subtype' 错误？

Question

我在尝试使用 Firestore 和 Stream Provider 时遇到以下错误

type '_JsonQueryDocumentSnapshot' is not a subtype of type 'Map<String, dynamic>' in type cast

这是我的根页面

ChangeNotifierProxyProvider<AuthProvider, DogProvider>(
      update: (context, value, previous) => DogProvider(), // ..getDogList()
      create: (_) => DogProvider(), //..getDogList()
    ),
    StreamProvider<Object>(
      create: (context) =>
          DogFirestoreService().getDogs('GeVnAbdq9BWs1STbytlAU65qkbc2'),
      initialData: 10,
      child: const DogsListScreen(),
    ),

我的 Firestore 服务获取流

Stream<List<DogModel>> getDogs(String uid) {
return dogCollection.where('userId', isEqualTo: uid).snapshots().map(
      (snapshot) => snapshot.docs
          .map((document) => DogModel.fromFire(document))
          .toList(),
    );

}

模特

 @JsonSerializable(explicitToJson: true)
class DogModel {
  String? dogImage;
  String dogName;
  DogBreed? breedInfo;
  @JsonKey(fromJson: dateTimeFromTimestamp, toJson: dateTimeAsIs)
  DateTime? dogBirthday;
  double? dogWeight;
  DogWeight? weightType;
  DogGender? dogGender;
  List<String>? dogType;
  DogStatus? dogStatus;
  bool? registered;
  String? dogChipId;
  @JsonKey(fromJson: dateTimeFromTimestamp, toJson: dateTimeAsIs)
  DateTime? createdAt;
  DogStats? dogStats;
  @JsonKey(ignore: true)
  String? id;
  String? userId;

  DogModel({
    required this.dogImage,
    required this.dogName,
    required this.breedInfo,
    required this.dogBirthday,
    required this.dogWeight,
    required this.weightType,
    required this.dogGender,
    required this.dogType,
    required this.dogStatus,
    required this.registered,
    this.dogStats,
    this.dogChipId,
    this.createdAt,
    this.userId,
    this.id,
  });

  factory DogModel.fromFire(QueryDocumentSnapshot snapshot) {
    return DogModel.fromJson(snapshot as Map<String, dynamic>);
  }

  // JsonSerializable constructor
  factory DogModel.fromJson(Map<String, dynamic> json) =>
      _$DogModelFromJson(json);

  // Serialization
  Map<String, dynamic> toJson() => _$DogModelToJson(this);
}

并在小部件中

Widget build(BuildContext context) {
final test = context.watch<Object>();
print(test);

Answer 1

正如我们在另一个中讨论的那样，您需要按如下方式从文档中提取数据：

Stream<List<DogModel>> getDogs(String uid) {
return dogCollection.where('userId', isEqualTo: uid).snapshots().map(
      (snapshot) => snapshot.docs
          .map((document) => DogModel.fromJson(document.data()) // <~~ here
          .toList(),
    );

如您所见，您应该调用 document.data()（而不是 document.data，这是我之前的错误）。

Flutter Firestore with Streams getting type '_JsonQueryDocumentSnapshot' is not a subtype' 错误？

Flutter Firestore with Streams getting type '_JsonQueryDocumentSnapshot' is not a subtype' error?

firebase

flutter

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