modus_json 是一个用于 Flutter 的 JSON 处理插件，它提供了一种简单且类型安全的方式来处理 JSON 数据。通过 modus_json，你可以轻松地将 JSON 数据转换为 Dart 对象，或者将 Dart 对象转换为 JSON 数据。

安装

首先，你需要在 pubspec.yaml 文件中添加 modus_json 依赖：

dependencies:
  flutter:
    sdk: flutter
  modus_json: ^0.1.0  # 请检查最新版本

然后运行 flutter pub get 来安装依赖。

基本用法

1. 定义数据模型

假设你有一个 JSON 数据如下：

{
  "id": 1,
  "name": "John Doe",
  "email": "johndoe@example.com",
  "isActive": true
}

你可以定义一个 Dart 类来表示这个数据模型：

import 'package:modus_json/modus_json.dart';

class User {
  final int id;
  final String name;
  final String email;
  final bool isActive;

  User({
    required this.id,
    required this.name,
    required this.email,
    required this.isActive,
  });

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'] as int,
      name: json['name'] as String,
      email: json['email'] as String,
      isActive: json['isActive'] as bool,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'name': name,
      'email': email,
      'isActive': isActive,
    };
  }
}

2. 使用 modus_json 进行序列化和反序列化

import 'package:modus_json/modus_json.dart';

void main() {
  // JSON 字符串
  String jsonString = '''
  {
    "id": 1,
    "name": "John Doe",
    "email": "johndoe@example.com",
    "isActive": true
  }
  ''';

  // 将 JSON 字符串反序列化为 User 对象
  User user = ModusJson.decode<User>(jsonString, (json) => User.fromJson(json));

  print('User ID: ${user.id}');
  print('User Name: ${user.name}');
  print('User Email: ${user.email}');
  print('Is Active: ${user.isActive}');

  // 将 User 对象序列化为 JSON 字符串
  String jsonOutput = ModusJson.encode(user, (user) => user.toJson());
  print('JSON Output: $jsonOutput');
}

高级用法

modus_json 还支持更复杂的 JSON 结构，例如嵌套对象、列表等。你可以通过定义嵌套的 fromJson 和 toJson 方法来处理这些情况。

嵌套对象示例

假设你有一个包含嵌套对象的 JSON：

{
  "id": 1,
  "name": "John Doe",
  "address": {
    "street": "123 Main St",
    "city": "Anytown",
    "zipcode": "12345"
  }
}

你可以定义如下的 Dart 类：

class Address {
  final String street;
  final String city;
  final String zipcode;

  Address({
    required this.street,
    required this.city,
    required this.zipcode,
  });

  factory Address.fromJson(Map<String, dynamic> json) {
    return Address(
      street: json['street'] as String,
      city: json['city'] as String,
      zipcode: json['zipcode'] as String,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'street': street,
      'city': city,
      'zipcode': zipcode,
    };
  }
}

class User {
  final int id;
  final String name;
  final Address address;

  User({
    required this.id,
    required this.name,
    required this.address,
  });

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'] as int,
      name: json['name'] as String,
      address: Address.fromJson(json['address'] as Map<String, dynamic>),
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'name': name,
      'address': address.toJson(),
    };
  }
}