Question

这是将要解码的json

    {
    "id": "RG-01-190919-00000001",
    "note": "",
    "items": null,
    "outlet": {
        "operational_times": [{
            "day_name": "Monday",
            "is_holiday": false,
            "operational_times": [{
                "time_to_open": "07.00",
                "time_to_close": "17.00"
            }]
        }]
    }
}

json来自我通过Web服务调用的数据库，并与诸如此类的未来构建器一起显示

    FutureBuilder(
  future: Http.getData(endpoint: "wsm/wsm_get_invoice_by_id_outlet_json.json",
            data: {"invoice_id": widget.idinvoice}),
  builder: (context, snapshot) {
       if (snapshot.hasData) {
          if (snapshot.data.toString() != "[]" &&
              snapshot.data != null) {

                var item = snapshot.data;
            }
        }
    }
)

但是当我像day_name一样在operational_times内部呼叫Text(item["outlet"]["operational_times"]["day_name"])时。出现错误

类型'String'不是'索引'的类型'int'的子类型

如果day_name位于数组中并包装在对象中，那么如何显示

Answer 1

如果您的json看起来像这样，并在getData（）中，则使用json.decode（jsonString）返回动态值
您可以在

下复制粘贴运行完整代码

 {
    "id": "RG-01-190919-00000001",
    "note": "",
    "items": null,
    "outlet": {
        "operational_times": [{
            "day_name": "Monday",
            "is_holiday": false,
            "operational_times": [{
                "time_to_open": "07.00",
                "time_to_close": "17.00"
            }]
        },
        {
            "day_name": "Tuesday",
            "is_holiday": false,
            "operational_times": [{
                "time_to_open": "07.00",
                "time_to_close": "17.00"
            }]
        }]
    }
}

代码段

FutureBuilder<dynamic>(
            future: getData(),
            builder: (BuildContext context, AsyncSnapshot<dynamic> snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.none:
                  return Text('Input a URL to start');
                case ConnectionState.waiting:
                  return Center(child: CircularProgressIndicator());
                case ConnectionState.active:
                  return Text('');
                case ConnectionState.done:
                  if (snapshot.hasError) {
                    return Text(
                      '${snapshot.error}',
                      style: TextStyle(color: Colors.red),
                    );
                  } else {
                    return ListView.builder(
                        itemCount: snapshot.data["outlet"]["operational_times"].length,
                        itemBuilder: (context, index) {
                          return ListTile(
                              title: Text(snapshot.data["outlet"]["operational_times"][index]["day_name"]),
                              );
                        });
                  }
              }
            })

工作演示

完整代码

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

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

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  Future<dynamic> getData() async {
    String jsonString = '''
    {
    "id": "RG-01-190919-00000001",
    "note": "",
    "items": null,
    "outlet": {
        "operational_times": [{
            "day_name": "Monday",
            "is_holiday": false,
            "operational_times": [{
                "time_to_open": "07.00",
                "time_to_close": "17.00"
            }]
        },
        {
            "day_name": "Tuesday",
            "is_holiday": false,
            "operational_times": [{
                "time_to_open": "07.00",
                "time_to_close": "17.00"
            }]
        }]
    }
}
    ''';

    return json.decode(jsonString);
    /*final response =  await http.get('http://api.open-notify.org/astros');

    if (response.statusCode == 200) {
      // If the call to the server was successful, parse the JSON.
      return json.decode(response.body);
    } else {
      // If that call was not successful, throw an error.
      throw Exception('Failed to load post');
    }*/
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
        appBar: AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our appbar title.
          title: Text(widget.title),
        ),
        body: FutureBuilder<dynamic>(
            future: getData(),
            builder: (BuildContext context, AsyncSnapshot<dynamic> snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.none:
                  return Text('Input a URL to start');
                case ConnectionState.waiting:
                  return Center(child: CircularProgressIndicator());
                case ConnectionState.active:
                  return Text('');
                case ConnectionState.done:
                  if (snapshot.hasError) {
                    return Text(
                      '${snapshot.error}',
                      style: TextStyle(color: Colors.red),
                    );
                  } else {
                    return ListView.builder(
                        itemCount: snapshot.data["outlet"]["operational_times"].length,
                        itemBuilder: (context, index) {
                          return ListTile(
                              title: Text(snapshot.data["outlet"]["operational_times"][index]["day_name"]),
                              );
                        });
                  }
              }
            }));
  }
}

在将来的构建器中解码json数组

1 个答案: