我正在从 Firebase 数据库获取数据并将其添加到我的模型类的列表中。我通过打印到控制台来测试传入的数据并且它工作正常,但是一旦我将数据添加到我的模型类,它就会消失。
这是我加载数据的 Provider 类。
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,
});
}
I'm getting the data until i added it to loadedRequest List
请帮忙,我在这上面花了好几个小时,但我不知道自己做错了什么。当我打印 loadedRequest 列表时,我得到一个空列表。谢谢。
最佳答案
这些日志没有显示空列表 - 它显示 [Instance of 'RequestModel']
。这意味着那里有 一个值,但 Dart 根本不知道如何将 RequestModel
转换为 String
以便它可以打印出来在控制台上。
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']
。
要更详细地打印出您的值,您可以覆盖类上的 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)";
}
关于flutter - 添加到模型时数据丢失,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/72584567/