如何解析嵌套 JSON - Flutter？答案

【问题标题】：How to parse Nested JSON - Flutter?如何解析嵌套 JSON - Flutter？
【发布时间】：2021-02-25 06:38:06
【问题描述】：

如何在不创建模型类的情况下解析这个 JSON 响应？

{"data":[{"Status":"0"}]}

我确实尝试将它作为jsonResponse['data']['Status'] 获取，但得到一个错误，指出未处理的异常：类型'String'不是'index'的'int'类型的子类型，但如果我只是尝试jsonResponse['data'] 我得到的结果是[{Status: 0}]

【问题讨论】：

标签： json flutter dart

【解决方案1】：

您可以在下面复制粘贴运行完整代码
[{"Status":"0"}] 是List
您可以使用jsonResponse["data"][0]["Status"]
代码sn-p

String jsonString = '''
    {"data":[{"Status":"0"}]}
    ''';

var jsonResponse = json.decode(jsonString);
print(jsonResponse["data"][0]["Status"]);

输出

I/flutter ( 6912): 0

完整代码

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

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

class MyApp extends StatelessWidget {  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(       
        primarySwatch: Colors.blue,        
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    String jsonString = '''
    {"data":[{"Status":"0"}]}
    ''';

    var jsonResponse = json.decode(jsonString);
    print(jsonResponse["data"][0]["Status"]);

    setState(() {     
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {    
    return Scaffold(
      appBar: AppBar(        
        title: Text(widget.title),
      ),
      body: Center(        
        child: Column(          
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), 
    );
  }
}

【讨论】：