Flutter JSON处理插件squint_json的使用

Flutter JSON处理插件squint_json的使用

概述

squint_json 是一个轻量级的JSON处理器和抽象语法树（AST）。它可以安全地将解码后的字符串反序列化为Dart类型。该库可以正确地解码嵌套列表，并且无需编写动态映射。

特性

• 正确反序列化JSON，包括嵌套数组。
• 不需要编写数据类即可反序列化JSON。
• 可以从JSON内容生成数据类。
• 可以通过编程方式生成用于JSON处理的样板代码。
• 可以通过命令行接口生成用于JSON处理的样板代码。
• 可以格式化JSON消息。
• 不需要 build_runner。
• 不需要 dart:mirrors。
• 可扩展：编写并重用自定义JSON数据转换器。

示例代码

以下是一个完整的示例代码，展示了如何使用 squint_json 插件来处理JSON数据。

// Copyright (c) 2021 - 2023 Buijs Software
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import 'package:squint_json/squint_json.dart';

/// 示例DTO，由用户定义。
[@squint](/user/squint)
class TestingExample {
  const TestingExample({
    required this.foo,
    required this.isOk,
    required this.random,
    required this.multiples,
  });

  final String foo;
  final bool isOk;
  final List<double> random;
  final List<List<String>> multiples;
}

/// Squint库生成的方法扩展
extension _TestExampleJsonBuilder on TestingExample {
  JsonObject get toJsonObject => JsonObject.fromNodes(nodes: [
    JsonString(key: "foo", data: foo),
    JsonBoolean(key: "isOk", data: isOk),
    JsonArray<dynamic>(key: "random", data: random),
    JsonArray<dynamic>(key: "multiples", data: multiples),
  ]);

  String get toJson => toJsonObject.stringify;
}

/// Squint库生成的方法扩展
extension _TestExampleJsonString2Class on String {
  TestingExample get toTestingExample => jsonDecode.toTestingExample;
}

/// Squint库生成的方法扩展
extension _TestExampleJsonObject2Class on JsonObject {
  TestingExample get toTestingExample => TestingExample(
    foo: stringNode("foo").data,
    isOk: booleanNode("isOk").data,
    random: arrayNode<double>("random").data,
    multiples: arrayNode<List<String>>("multiples").data,
  );
}

void main() {
  const example = """
  {
    "foo": "squint",
    "isOk": true,
    "random" : [
        0.0,
        3.0,
        2.0
    ],
    "multiples" : [
        [
            "hooray!"
        ]
    ]
  }""";

  final response = example.toTestingExample;
  print("foo is ${response.foo}"); // 输出: foo is squint.
  print("isOk is ${response.isOk}"); // 输出: isOk is true.
  print("random is ${response.random}"); // 输出: random is [0.0,3.0,2.0].
  print("multiples is ${response.multiples}"); // 输出: multiples is [[hooray!]].
}

使用说明

1. 定义数据模型：

   [@squint](/user/squint)
   class TestingExample {
     const TestingExample({
       required this.foo,
       required this.isOk,
       required this.random,
       required this.multiples,
     });
   
     final String foo;
     final bool isOk;
     final List<double> random;
     final List<List<String>> multiples;
   }
   

2. 生成用于JSON处理的扩展方法：

   extension _TestExampleJsonBuilder on TestingExample {
     JsonObject get toJsonObject => JsonObject.fromNodes(nodes: [
       JsonString(key: "foo", data: foo),
       JsonBoolean(key: "isOk", data: isOk),
       JsonArray<dynamic>(key: "random", data: random),
       JsonArray<dynamic>(key: "multiples", data: multiples),
     ]);
   
     String get toJson => toJsonObject.stringify;
   }
   
   extension _TestExampleJsonString2Class on String {
     TestingExample get toTestingExample => jsonDecode.toTestingExample;
   }
   
   extension _TestExampleJsonObject2Class on JsonObject {
     TestingExample get toTestingExample => TestingExample(
       foo: stringNode("foo").data,
       isOk: booleanNode("isOk").data,
       random: arrayNode<double>("random").data,
       multiples: arrayNode<List<String>>("multiples").data,
     );
   }
   

3. 使用JSON字符串进行反序列化：

   void main() {
     const example = """
     {
       "foo": "squint",
       "isOk": true,
       "random" : [
           0.0,
           3.0,
           2.0
       ],
       "multiples" : [
           [
               "hooray!"
           ]
       ]
     }""";
   
     final response = example.toTestingExample;
     print("foo is ${response.foo}"); // 输出: foo is squint.
     print("isOk is ${response.isOk}"); // 输出: isOk is true.
     print("random is ${response.random}"); // 输出: random is [0.0,3.0,2.0].
     print("multiples is ${response.multiples}"); // 输出: multiples is [[hooray!]].
   }