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Convert JSON into POJO (Object) similar to android in Flutter

由 自作多情 提交于 2019-12-05 20:01:01

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.

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

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.

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!

标签
android
json
parsing
Flutter
pojo
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