Flutter数据转换插件transformer_simplified的使用

Flutter数据转换插件transformer_simplified的使用

Transformer Simplified 是一个简单的库，用于在 JSON 结构之间进行映射和转换。考虑到 JSON 结构是一个 Map<String, dynamic> 类型，此库可以用来转换任何这种类型的映射。

示例代码

以下是一个完整的示例，展示了如何使用 TransformerSimplified 进行数据转换。

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart'; // 引入路径提供者
import 'package:transformer_simplified/transformer_simplified.dart';

void main() async {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("Transformer Simplified Example")),
        body: Center(
          child: ElevatedButton(
            onPressed: () async {
              dynamic jsonData = json.decode(await File('./example/mapping.json').readAsString());
              TransformerRegistry.get().setCustom('revert', Revert());

              TransformerSimplified.get().load('mapping', jsonData);

              String key1LowerCase = 'david lower case';
              String streetUpperCase = 'STREET IN UPPERCASE';
              String zipCodeAsString = '10000';
              String otherZipCode = 'other cedex in lowercase';
              Map<String, dynamic> input = {
                'key1': key1LowerCase,
                'key2': [
                  {
                    'street': streetUpperCase,
                    'zipcode': zipCodeAsString,
                    'city': 'myCity',
                    'alias': {'otherZipCode': 'cedex in lowercase'}
                  },
                  {
                    'street': 'STREET2 IN UPPERCASE2',
                    'zipcode': '30000',
                    'city': 'yourCity',
                    'alias': {'otherZipCode': otherZipCode}
                  }
                ],
              };

              dynamic output = TransformerSimplified.get()
                  .execute(input, 'formUserToJSonUser', 'mapping');

              print(output);
            },
            child: Text("执行转换"),
          ),
        ),
      ),
    );
  }
}

JSON 映射配置

以下是用于映射和转换的 JSON 配置文件示例：

[
  {
    "id": "formUserToJSonUser",
    "mappings": [
      {
        "type": "single",
        "input": {
          "path": "key1"
        },
        "output": {
          "path": "name1"
        },
        "transformer": "builtin://toUppercase"
      },
      {
        "type": "complex",
        "list": true,
        "input": {
          "path": "key2"
        },
        "output": {
          "path": "addresses",
          "comment": "列表类型要么是从第一个根类型中推断出来的类型，要么是 Map<String, dynamic> 如果输出是 map/list 且没有预定义的类型"
        },
        "transformer": "mapping://map2Address"
      }
    ]
  },
  {
    "id": "map2Address",
    "mappings": [
      {
        "type": "single",
        "input": {
          "path": "street"
        },
        "output": {
          "path": "street"
        },
        "transformer": "builtin://toLowercase"
      },
      {
        "type": "single",
        "input": {
          "path": "zipcode"
        },
        "output": {
          "path": "ZipCode"
        },
        "transformer": "builtin://toInteger"
      },
      {
        "type": "single",
        "input": {
          "path": "city"
        },
        "output": {
          "path": "city"
        }
      },
      {
        "type": "complex",
        "input": {
          "path": "alias"
        },
        "output": {
          "path": "alias"
        },
        "transformer": "mapping://mappingAlias"
      }
    ]
  },
  {
    "id": "mappingAlias",
    "mappings": [
      {
        "type": "single",
        "input": {
          "path": "otherZipCode"
        },
        "output": {
          "path": "newZipCode"
        },
        "transformer": "custom://revert"
      }
    ]
  }
]

Dart 代码解释

1. 导入必要的包：

   import 'dart:convert';
   import 'package:flutter/material.dart';
   import 'package:path_provider/path_provider.dart';
   import 'package:transformer_simplified/transformer_simplified.dart';
   

2. 读取 JSON 文件并解析：

   dynamic jsonData = json.decode(await File('./example/mapping.json').readAsString());
   

3. 注册自定义转换器：

   TransformerRegistry.get().setCustom('revert', Revert());
   

4. 加载映射配置：

   TransformerSimplified.get().load('mapping', jsonData);
   

5. 准备输入数据：

   Map<String, dynamic> input = {
     'key1': key1LowerCase,
     'key2': [
       {
         'street': streetUpperCase,
         'zipcode': zipCodeAsString,
         'city': 'myCity',
         'alias': {'otherZipCode': 'cedex in lowercase'}
       },
       {
         'street': 'STREET2 IN UPPERCASE2',
         'zipcode': '30000',
         'city': 'yourCity',
         'alias': {'otherZipCode': otherZipCode}
       }
     ],
   };
   

6. 执行转换：

   dynamic output = TransformerSimplified.get()
       .execute(input, 'formUserToJSonUser', 'mapping');