每當我嘗試訪問嵌套陣列中的欄位時，我都會收到以下 Range 錯誤。不知道出了什么問題，任何幫助將不勝感激。
RangeError (index): Invalid value: Only valid value is 0: 1
這是我的用戶模型：
import 'dart:convert';
List<User> userFromJson(String str) =>
List<User>.from(json.decode(str).map((x) => User.fromJson(x)));
class User {
User({
required this.userName,
required this.facilities,
});
final String userName;
final List<Facility>? facilities;
factory User.fromJson(Map<String, dynamic> json) => User(
userName: json["userName"],
facilities: json["facilities"] == null
? null
: List<Facility>.from(
json["facilities"].map((x) => Facility.fromJson(x))),
);
}
class Facility {
Facility({
required this.id,
required this.employeeGlobalId,
required this.facilityId,
});
final int id;
final int employeeGlobalId;
final int facilityId;
factory Facility.fromJson(Map<String, dynamic> json) => Facility(
id: json["id"],
employeeGlobalId: json["employeeGlobalId"],
facilityId: json["facilityId"],
);
}
這就是我連接 API 并將回應轉換為串列的方式。
class ApiService {
final url = Uri.parse("http://47.254.237.237:81/api/Users/GetAllUser");
Map<String, String> headers = {
"Accept": 'application/json',
'content-type': 'application/json',
'Authorization':
'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjYyIiwibmJmIjoxNjY2OTU0NTEzLCJleHAiOjE2NjcwNDA5MTMsImlhdCI6MTY2Njk1NDUxM30.EXEzTX8-MHQqZuuILwHGoQ0Vpw2fAgsi2QypGNFgMAE',
'userId': '62'
};
Future<List<User>> fetchUsers(http.Client client) async {
final response = await client.get(url, headers: headers);
return compute(parseUsers, response.body);
}
List<User> parseUsers(String response) {
final parsed = jsonDecode(response).cast<Map<String, dynamic>>();
return parsed.map<User>((json) => User.fromJson(json)).toList();
}
}
最后，這就是我試圖顯示設施 ID 的方式。
ListView.builder(
itemBuilder: (context, index) {
return ListTile(
title: Text(users[index].userName),
subtitle: Text(users[index].facilities![index].facilityId.toString()),
);
},
);
uj5u.com熱心網友回復：
可能facilities![index]是導致問題的原因。您正在嘗試訪問范圍內的facilities值，而可能只有一個值可用。indexbuilder's current position
更改為facilities![0]。如果設施值超過 1 個，則使用 loop/map fn 列印每個設施。
更新代碼：
ListView.builder(
itemBuilder: (context, index) {
return ListTile(
title: Text(users[index].userName),
subtitle: Text(users[index].facilities![0].facilityId.toString()),
);
},
);
轉載請註明出處，本文鏈接：https://www.uj5u.com/shujuku/526225.html
標籤：扑镖
下一篇：從firebase下載并顯示影像