添加到模型时数据丢失

Question

我从Firebase数据库获取数据并将其添加到我的模型类列表中。我通过打印到控制台来测试传入的数据，它工作得很好，但是一旦我将数据添加到模型类中，它就消失了。

这是我的Provider类，我在这里加载数据。

import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:local_stuffs_notification/apis/fcm.dart';
import 'package:local_stuffs_notification/models/request_model.dart';
import 'package:shared_preferences/shared_preferences.dart';
class IncomingRequest with ChangeNotifier {
List<RequestModel> _incomingRequests = [];
IncomingRequest(this._incomingRequests);
List<RequestModel> get incomingRequest {
return [..._incomingRequests];
}
Future<void> setIncomingRequest(RequestModel requestModel) async {
try {
DatabaseReference reference =
FirebaseDatabase.instance.ref("incomingRequests");
reference.child(requestModel.id).child(Fcm.getUid()).set(
{
"name": requestModel.name.toString(),
"phone": requestModel.phone.toString(),
"email": requestModel.email.toString(),
"fcmToken": requestModel.fcmToken.toString(),
},
);
notifyListeners();
} catch (error) {
rethrow;
}
}
Future<void> loadIncomingRequests() async {
try {
SharedPreferences preferences = await SharedPreferences.getInstance();
DatabaseReference reference = FirebaseDatabase.instance
.ref('incomingRequests/${preferences.getString('userId')!}');
Stream<DatabaseEvent> stream = reference.onValue;
stream.listen((DatabaseEvent event) {
print(event.snapshot.value);
final data = event.snapshot.value as Map;
print('data: $data');
final List<RequestModel> loadedRequest = [];
data.forEach(
(key, value) {
print('requestData: ${value['name']}');
loadedRequest.add(
RequestModel(
id: key.toString(),
name: value['name'].toString(),
fcmToken: value['fcmToken'].toString(),
phone: value['phone'].toString(),
email: value['email'].toString(),
),
);
print(loadedRequest);
},
);
_incomingRequests = loadedRequest;
print('LoadedRequests: $loadedRequest');
notifyListeners();
});
// reference.onValue.listen(
//   (event) {
//     if (event.snapshot.value == null) {
//       return;
//     }
//     final data = event.snapshot.value as Map;
//     final List<RequestModel> loadedRequests = [];
//     data.forEach(
//       (key, requestData) {
//         loadedRequests.add(
//           RequestModel(
//             id: key,
//             name: requestData['name'],
//             fcmToken: requestData['fcmToken'],
//             phone: requestData['phone'],
//             email: requestData['email'],
//           ),
//         );
//       },
//     );
//     _incomingRequests = loadedRequests;
//     notifyListeners();
// },
//);
} catch (error) {
rethrow;
}
}
}

这是我的模型类

class RequestModel {
final String id;
final String name;
final String fcmToken;
final String phone;
final String email;
RequestModel({
required this.id,
required this.name,
required this.fcmToken,
required this.phone,
required this.email,
});
}

我得到的数据，直到我添加到加载请求列表

请帮忙，我花了几个小时在这上面，我不知道我做错了什么。当我打印加载请求列表时，我得到一个空列表。谢谢。

Answer 1

这些日志没有显示空列表-它显示[Instance of 'RequestModel']。这意味着在那里是一个值，但是Dart根本不知道如何将RequestModel转换为String，以便可以在控制台上打印出来。

空列表将简单地打印为[]，如果您有两个值，例如，您将看到[Instance of 'RequestModel', Instance of 'RequestModel']。

要打印出更详细的值，可以覆盖类上的toString()方法。

例如:

class RequestModel {
final String id;
final String name;
final String fcmToken;
final String phone;
final String email;
RequestModel({
required this.id,
required this.name,
required this.fcmToken,
required this.phone,
required this.email,
});
@override
String toString() => 
"RequestModel(id: $id, name: $name, fcmToken: $fcmToken, phone: $phone, email: $email)";
}

Answer 2

再次查看原始数据，它包含所有用户数据，因此您需要在名称

之前访问uid

final uid = FirebaseAuth.instance.currentUser!.uid;

，然后对于RequestModel:

name: data[uid]['name']