如何将嵌套的 Json 作为来自 Flutter 的 http 发布请求发送到正文中

Question

我正在尝试在我一直在开发的颤振应用程序的一个 http post 请求中发送一个嵌套的 Json 作为正文。

{
      "user" : {
        "UserName": "username",
        "password":"password",
        "Name": "name",
        "Email": "email"
      }
}

我尝试了许多在线可用的方法来执行此操作，但每次都收到 500 错误。下面是一个将其转换为 Json 的类。

class SignupJson {
  String username;
  String email;
  String name;
  String password;

  SignupJson(this.email, this.name, this.password, this.username);

  Map toJson() =>{"user":{
    'UserName': username,
    'Name': name,
    'password': password,
    'Email': email
  }};

}

并将其传递给此以进行发布请求。 （我放了一个任意的url链接）

Future<int> attemptSignup ({String username, String password, String name, String email}) async {



    SignupJson data = SignupJson(username: username, password: password, name: name, email: email);
    var url = 'url';

    String body = jsonEncode(json);

    var res = await http.post(url,
    body: body);
    return res.statusCode;

  }

Answer 1

我根据这个json编码：

{
"user": {
    "UserName": "username",
    "password": "password",
    "Name": "name",
    "Email": "email"
  }
 }

您的 Post Api 调用如下：

 Future<User> postUser(String username, String password, String name, String 
 email) async {

 Paste your api url here
 String url = '';
   final response = await http.post(apiUrl, headers: {
   // Enter your headers parameter if needed
   //  E.g: 
   'Authorization' : 'xyz',
   'Content-Type' : 'application/json'
 },
 body: jsonEncode(<String, String>{
   'UserName' : username,
   'password' : password,
   'Name' : name,
   'Email' : email
  }));

 if (response.statusCode == 200) {
    var data = jsonDecode(response.body.toString());
    print(data);
    return User.fromJson(jsonDecode(response.body));
  } else {
   throw Exception('Failed to post user.');
  }
}

你的模型是这样的：

  class User {
     User? user;

     User({this.user});

     User.fromJson(Map<String, dynamic> json) {
       user = json['user'] != null ? new User.fromJson(json['user']) : null;
     }

    Map<String, dynamic> toJson() {
      final Map<String, dynamic> data = new Map<String, dynamic>();
      if (this.user != null) {
        data['user'] = this.user!.toJson();
      }
      return data;
     }
   }

  class User {
    String? userName;
    String? password;
    String? name;
    String? email;

      User({this.userName, this.password, this.name, this.email});

      User.fromJson(Map<String, dynamic> json) {
       userName = json['UserName'];
       password = json['password'];
       name = json['Name'];
       email = json['Email'];
     }

    Map<String, dynamic> toJson() {
       final Map<String, dynamic> data = new Map<String, dynamic>();
        data['UserName'] = this.userName;
        data['password'] = this.password;
        data['Name'] = this.name;
       data['Email'] = this.email;
      return data;
     }
    }

Answer 2

过去 2 天我一直被这个问题困扰。以下是我克服问题的方法

Future<int> attemptSignup ({String username, String password, String name, String email}) async {


SignupJson data = SignupJson(username: username, password: password, name: name, email: email);
var url = 'url';

String body = jsonEncode(data);     

//here jsonEncode(data) return String bt in http body you are passing Map value

//So you have to convert String to Map
Map bodyMap = jsonDecode(body);         

// your nested json data
var bodyData = {       // where var store <String, dynamic> data as your demand
      "user" : bodyMap  
};


var res = await http.post(url,
body: bodyData,
headers: {"Content-Type": "application/json",},
);

return res.statusCode;

}

确保在 http 中添加标头

Answer 3

将地图定义为<String, dynamic> 例如：

Map<String, dynamic> data = {
"User": {
          "UserName":"username",
          "Password":"password"
    }
};

并在标题中添加以下内容：

HttpClient httpClient = new HttpClient();
HttpClientRequest request = await httpClient.postUrl(Uri.parse(url));
request.headers.set('Accept', 'application/json');
request.headers.set('Content-type', 'application/json');
request.add(utf8.encode(json.encode(data)));
HttpClientResponse response = await request.close();
String reply = await utf8.decoder.bind(response).join();
httpClient.close();

Answer 4

像这样添加标题：

Map<String, String> headers = {HttpHeaders.contentTypeHeader: "application/json"};

然后在 post 请求中：

var res = await http.post(url, headers: headers, body: body);