如何解析 flutter 中的 graphql 响应

Question

我正在尝试在我的 flutter 应用程序中解析来自 neo4j-graphql 后端的 graphql 响应。我正在使用 flutter_graphql 插件向后端进行查询。但是，当我尝试解析响应（JSON）时，我收到“LinkHashMap 不是用户映射的子类型”。

我尝试修改我的序列化类来解析响应，但没有可用的。下面是来自 neo4j graphql 的 JSON 响应

 /*I HAVE EDITED THE JSON RESPONSE. THE FULL JSON RESPONSE FROM THE SERVER IS AS BELOW*/
{
  "data": {
    "User": [
      {
        "userId": 1,
        "city": "NewYork",
        "country": "User",
        "captionType": "User",
        "state": "New York",
        "firstName": "example2",
        "lastname": "example",
        "email": "example2@gmail.com"
      }
    ]
  },
  "extensions": {
    "type": "READ_ONLY"
  }
}

下面是代表上述响应的类

 /*I HAVE EDITED THE JSON RESPONSE. THE FULL JSON RESPONSE FROM THE SERVER IS AS BELOW*/
{
  "data": {
    "User": [
      {
        "userId": 1,
        "city": "NewYork",
        "country": "User",
        "captionType": "User",
        "state": "New York",
        "firstName": "example2",
        "lastname": "example",
        "email": "example2@gmail.com"
      }
    ]
  },
  "extensions": {
    "type": "READ_ONLY"
  }
}

我期望通过 Users 类解析信息并通过 listViewWidget 显示信息。但是我得到“LinkHashMap 不是用户映射的子类型”。

Answer 1

您可以使用https://app.quicktype.io/解析任何 JSON ，下面是 JSON 的模型类

// To parse this JSON data, do
//
//     final responseModel = responseModelFromJson(jsonString);

import 'dart:convert';

ResponseModel responseModelFromJson(String str) => ResponseModel.fromJson(json.decode(str));

String responseModelToJson(ResponseModel data) => json.encode(data.toJson());

class ResponseModel {
Data data;
Extensions extensions;

ResponseModel({
    this.data,
    this.extensions,
});

factory ResponseModel.fromJson(Map<String, dynamic> json) => ResponseModel(
    data: json["data"] == null ? null : Data.fromJson(json["data"]),
    extensions: json["extensions"] == null ? null : Extensions.fromJson(json["extensions"]),
);

Map<String, dynamic> toJson() => {
    "data": data == null ? null : data.toJson(),
    "extensions": extensions == null ? null : extensions.toJson(),
    };
}

class Data {
List<User> user;

Data({
    this.user,
});

factory Data.fromJson(Map<String, dynamic> json) => Data(
    user: json["User"] == null ? null : List<User>.from(json["User"].map((x) => User.fromJson(x))),
);

Map<String, dynamic> toJson() => {
    "User": user == null ? null : List<dynamic>.from(user.map((x) => x.toJson())),
    };
}

class User {
int userId;
String city;
String country;
String captionType;
String state;
String firstName;
String lastname;
String email;

User({
    this.userId,
    this.city,
    this.country,
    this.captionType,
    this.state,
    this.firstName,
    this.lastname,
    this.email,
});

factory User.fromJson(Map<String, dynamic> json) => User(
    userId: json["userId"] == null ? null : json["userId"],
    city: json["city"] == null ? null : json["city"],
    country: json["country"] == null ? null : json["country"],
    captionType: json["captionType"] == null ? null : json["captionType"],
    state: json["state"] == null ? null : json["state"],
    firstName: json["firstName"] == null ? null : json["firstName"],
    lastname: json["lastname"] == null ? null : json["lastname"],
    email: json["email"] == null ? null : json["email"],
);

Map<String, dynamic> toJson() => {
    "userId": userId == null ? null : userId,
    "city": city == null ? null : city,
    "country": country == null ? null : country,
    "captionType": captionType == null ? null : captionType,
    "state": state == null ? null : state,
    "firstName": firstName == null ? null : firstName,
    "lastname": lastname == null ? null : lastname,
    "email": email == null ? null : email,
    };
}

class Extensions {
String type;

Extensions({
    this.type,
});

factory Extensions.fromJson(Map<String, dynamic> json) => Extensions(
    type: json["type"] == null ? null : json["type"],
);

Map<String, dynamic> toJson() => {
    "type": type == null ? null : type,
    };
}

使用此代码来解析您的响应

ResponseModel  responseModel = responseModelFromJson(result.data);
return listViewWidget(responseModel.data.user);