问题
I'm just trying to find a way to convert a json response (from a REST API) into POJO (As used in android) so that I can use the received data into my application as using Map wont be sufficient as the data i'm receiving is a little complex and contains 3 levels of arrays (arrays inside of arrays inside of arrays).
I'm using Dio library for api calls and i can make API call successfully and print the data on the console with no issues at all. Can anyone assist me in achieving this?
Below is the response i'm getting.
{
"status": 200,
"message": "success",
"data": [
{
"menu": {
"megamenu_id": "55",
"language_id": "1",
"title": "Mobiles",
"description": "",
"submenu": [
{
"0": {
"info": {
"megamenu_id": "67",
"language_id": "1",
"title": "Mobile Phones",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "68",
"language_id": "1",
"title": "Android Phones",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "69",
"language_id": "1",
"title": "Smart Phones",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "70",
"language_id": "1",
"title": "Windows Phones",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "72",
"language_id": "1",
"title": "Basic Phones",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "73",
"language_id": "1",
"title": "Latest Mobiles",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "74",
"language_id": "1",
"title": "Upcoming Mobiles",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "75",
"language_id": "1",
"title": "Brands",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "76",
"language_id": "1",
"title": "Samsung",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "77",
"language_id": "1",
"title": "Apple",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "78",
"language_id": "1",
"title": "Redmi",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "79",
"language_id": "1",
"title": "Nokia",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "81",
"language_id": "1",
"title": "Sony",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "82",
"language_id": "1",
"title": "Micromax",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "83",
"language_id": "1",
"title": "HTC",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "84",
"language_id": "1",
"title": "Motorola",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "85",
"language_id": "1",
"title": "Oppo",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "86",
"language_id": "1",
"title": "Vivo",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "87",
"language_id": "1",
"title": "Honor",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "88",
"language_id": "1",
"title": "Oneplus",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "94",
"language_id": "1",
"title": "Mobile Accessories",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "95",
"language_id": "1",
"title": "Bluetooth Headsets",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "96",
"language_id": "1",
"title": "Mobile Chargers",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "97",
"language_id": "1",
"title": "Mobiles Cases & Covers",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "98",
"language_id": "1",
"title": "Screen Protector",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "99",
"language_id": "1",
"title": "Mobile Batteries",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "100",
"language_id": "1",
"title": "Headphones & Headsets",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "101",
"language_id": "1",
"title": "Memory Cards",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "102",
"language_id": "1",
"title": "Power Banks",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "103",
"language_id": "1",
"title": "Stylus",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "104",
"language_id": "1",
"title": "Mobile Docks",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "107",
"language_id": "1",
"title": "Features",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "108",
"language_id": "1",
"title": "Dual Sim Phones",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "111",
"language_id": "1",
"title": "4GB Ram Mobiles",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "112",
"language_id": "1",
"title": "Rear Camera [13 MP]",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "113",
"language_id": "1",
"title": "Screen Size [4.5 - 5.2 Inch]",
"description": ""
}
}
]
}
]
}
},
{
"menu": {
"megamenu_id": "168",
"language_id": "1",
"title": "Fashion",
"description": "",
"submenu": [
{
"0": {
"info": {
"megamenu_id": "169",
"language_id": "1",
"title": "Clothing",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "170",
"language_id": "1",
"title": "T-Shirts",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "171",
"language_id": "1",
"title": "Shirts",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "178",
"language_id": "1",
"title": "Womens Clothing",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "187",
"language_id": "1",
"title": "Night Wear",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "188",
"language_id": "1",
"title": "Tunics",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "189",
"language_id": "1",
"title": "Kurtis",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "190",
"language_id": "1",
"title": "Sarees",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "191",
"language_id": "1",
"title": "Lehengas",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "192",
"language_id": "1",
"title": "Swimming Suit",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "193",
"language_id": "1",
"title": "Men's Footwear",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "194",
"language_id": "1",
"title": "Shoes",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "195",
"language_id": "1",
"title": "Sneakers",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "196",
"language_id": "1",
"title": "Sandals & Floaters",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "197",
"language_id": "1",
"title": "Slippers & Flip Flops",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "198",
"language_id": "1",
"title": "Loafers",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "199",
"language_id": "1",
"title": "Boots",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "200",
"language_id": "1",
"title": "Shoe Care",
"description": ""
}
}
]
},
{
"0": {
"info": {
"megamenu_id": "201",
"language_id": "1",
"title": "Women's Jewellery",
"description": ""
}
},
"subsubmenu": [
{
"infosub": {
"megamenu_id": "202",
"language_id": "1",
"title": "Earrings",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "203",
"language_id": "1",
"title": "Bangles",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "204",
"language_id": "1",
"title": "Bracelets",
"description": ""
}
},
{
"infosub": {
"megamenu_id": "205",
"language_id": "1",
"title": "Rings",
"description": ""
}
}
]
}
]
}
},
{
"menu": {
"megamenu_id": "220",
"language_id": "1",
"title": "Care",
"description": ""
}
},
{
"menu": {
"megamenu_id": "221",
"language_id": "1",
"title": "Offers",
"description": ""
}
},
{
"menu": {
"megamenu_id": "222",
"language_id": "1",
"title": "News",
"description": ""
}
}
]
}
回答1:
Android studio plugin : https://plugins.jetbrains.com/plugin/11460-json2dart/
Online: https://javiercbk.github.io/json_to_dart/
Manually parse : https://medium.com/flutter-community/parsing-complex-json-in-flutter-747c46655f51
Generate Dart classes from json
Convert JSON to Dart class
Generate Dart class from JSON or JSON-Schema.
回答2:
json_serializable isn't that well documented, but it does exactly what you want, is easier to use and requires less boilerplate than built_value, especially when it comes to arrays.
import 'package:json_annotation/json_annotation.dart';
import 'dart:convert';
part 'school.g.dart';
@JsonSerializable()
class School {
final String name;
final int maxStudentCount;
final List<Student> students;
School(this.name, this.maxStudentCount, this.students);
factory School.fromJson(Map<String, dynamic> json) => _$SchoolFromJson(json);
Map<String, dynamic> toJson() => _$SchoolToJson(this);
}
@JsonSerializable()
class Student {
final String name;
final DateTime birthDate;
Student({this.name, this.birthDate});
factory Student.fromJson(Map<String, dynamic> json) => _$StudentFromJson(json);
Map<String, dynamic> toJson() => _$StudentToJson(this);
}
test() {
String jsonString = '''{
"name":"Trump University",
"maxStudentCount":9999,
"students":[
{
"name":"Peter Parker",
"birthDate":"1999-01-01T00:00:00.000Z"
}
]
}''';
final decodedJson = json.decode(jsonString);
final school = School.fromJson(decodedJson);
assert(school.students.length == 1);
}
It also supports enum serialization.
To generate the serialization code, run:
flutter packages pub run build_runner build
回答3:
This can be done using built_value. Detailed documentation is available in this link.
You just have to write some boilerplate code and run this command flutter packages pub run build_runner build.
Below is a sample class like POJO.
import 'package:built_value/built_value.dart';
import 'package:built_value/serializer.dart';
part 'auth.g.dart';
abstract class Auth implements Built<Auth, AuthBuilder> {
static Serializer<Auth> get serializer => _$authSerializer;
String get currentServerTime;
int get defaultOrganization;
String get tokenExpiryTimeInMs;
bool get rememberMe;
int get failedLoginAttempts;
int get userId;
String get status;
String get token;
Auth._();
factory Auth([updates(AuthBuilder b)]) = _$Auth;
}
Below is the Serializer class:
library serializers;
import 'package:built_value/serializer.dart';
import 'package:built_value/standard_json_plugin.dart';
import 'auth/auth.dart';
part 'serializers.g.dart';
@SerializersFor(const [
Auth,
])
Serializers serializers = _$serializers;
Serializers standardSerializers =
(serializers.toBuilder()..addPlugin(StandardJsonPlugin())).build();
Below is the code where conversion from JSON to Object takes place.
Auth auth = standardSerializers.deserializeWith(
Auth.serializer, json.decode(res.body)['user']);
Hope this helps.
回答4:
SO, after some tries with the json_serializable library, I came up with my own solution and it doesnt require any external library at all and works like a charm. This way i had to write less boilerplate code and i think is a clean way to do this.
Here's how to make the model
class SideMenuRes {
final int status;
final String message;
final List<SideMenuDatum> sideMenuData;
SideMenuRes({this.status, this.message, this.sideMenuData});
factory SideMenuRes.fromJson(Map json) {
return SideMenuRes(
status: json['status'],
message: json['message'],
sideMenuData: json['status'] == 200 ? (json['data'] as List).map((i) => new
SideMenuDatum.fromJson(i)).toList() : null,
);
}
}
class SideMenuDatum {
final Menu menu;
SideMenuDatum({this.menu});
factory SideMenuDatum.fromJson(Map json) {
return SideMenuDatum(
menu: Menu.fromJson(json['menu']),
);
}
}
class Menu {
final String megamenu_id;
final String language_id;
final String title;
final String description;
final List<SubMenu> subMenu;
Menu({this.megamenu_id, this.language_id, this.title, this.description, this.subMenu});
factory Menu.fromJson(Map json) {
return Menu(
megamenu_id: json['megamenu_id'],
language_id: json['language_id'],
title: json['title'],
description: json['description'],
subMenu: json['submenu'] != null ? (json['submenu'] as List).map((i) => new SubMenu.fromJson(i)).toList() : null
);
}
}
class SubMenu {
final Zero zero;
final List<SubSubMenu> subSubMenu;
SubMenu({this.zero, this.subSubMenu});
factory SubMenu.fromJson(Map json) {
return SubMenu(
zero: Zero.fromJson(json['0']),
subSubMenu: (json['subsubmenu'] as List).map((i) => new SubSubMenu.fromJson(i)).toList()
);
}
}
class Zero {
final Info info;
Zero({this.info});
factory Zero.fromJson(Map json) {
return Zero(
info: Info.fromJson(json['info']),
);
}
}
class SubSubMenu {
final InfoSub infoSub;
SubSubMenu({this.infoSub});
factory SubSubMenu.fromJson(Map json) {
return SubSubMenu(
infoSub: InfoSub.fromJson(json['infosub'])
);
}
}
class InfoSub {
final String megamenu_id;
final String language_id;
final String title;
final String description;
InfoSub({this.megamenu_id, this.language_id, this.title, this.description});
factory InfoSub.fromJson(Map json) {
return InfoSub(
megamenu_id: json['megamenu_id'],
language_id: json['language_id'],
title: json['title'],
description: json['description']
);
}
}
class Info {
final String megamenu_id;
final String language_id;
final String title;
final String description;
Info({this.megamenu_id, this.language_id, this.title, this.description});
factory Info.fromJson(Map json) {
return Info(
megamenu_id: json['megamenu_id'],
language_id: json['language_id'],
title: json['title'],
description: json['description']
);
}
}
And calling it like this
SubMenuRes subMenuRes = SubMenuRes.fromJson(response.data);
That's it!
来源：https://stackoverflow.com/questions/51901760/convert-json-into-pojo-object-similar-to-android-in-flutter