未处理的异常：类型 '_InternalLinkedHashMap<String, dynamic>' 不是类型 'Iterable<dynamic>' 的子类型 为什么会出现此错误

Question

api响应json复杂时如何从api加载值到字段？

  {  
  "agent":{
    "agent_name": "Shamsudheen",
    "agent_phone": "0581476710",
    "email": "shamsu@gmail.com",
          },
   "tenants": [
    {
        "entity_id": "152",
        "user_id": "37",
    },
    {
        "entity_id": "153",
        "user_id": "37",
    },
    {
        "entity_id": "150",
        "user_id": "37",
    }
 ]
}

这是我的模型类

 class AgentDetailsInfo {
 String name;
 String email;
 String mobile;   
 List<Tenantdetails> list;
 AgentDetailsInfo(
  {
  this.name,
  this.email,
  this.mobile,
  this.list
   });
  factory AgentDetailsInfo.fromJson(Map<String, dynamic> json) {
  return new AgentDetailsInfo(
    name: json['agent']['agent_name'],
    email: json['agent']['email'],
    mobile: json['agent']['agent_phone']
    List:json[’tenants’]
   );
      }
     }

class Tenantdetails {
 String entity;
 String userid;
 Tenantdetails({
  this.entity,
  this.userid,
  });
    factory Tenantdetails.fromJson(Map<String, dynamic> json) {
     return new Tenantdetails(
      entity: json['tenants']['entity_id'],
      userid: json['tenants']['user_id'],
     );
   }
 }

并且我正在调用 api 就像这个响应完美但价值是 nitf

  List<AgentDetailsInfo> _list;
  Future getAgentDetails(String agentId) async {
  String tokenKey = await SharedPrefUtils.readPrefStr("token");
  String url =
  Constants.BASEURL + Constants.KEYWORD_GET_AGENT_DETAILS + agentId;
  final response = await http.get(
  url,
  headers: {"Accept": "application/json", "Authorization": tokenKey},
  );

  var response =  jsonDecode(response.body);

  _list = List();
    for (Map agentinfo in response) {
    _list.add(AgentDetailsInfo.fromJson(agentinfo));
  }
 }

但它没有加载到我的文本视图中显示错误 "_InternalLinkedHashMap' 不是“Iterable”类型的子类型

Text(_list[0].name,
  ))

Answer 1

您可以在下面复制粘贴运行完整代码
第 1 步：根据您的 JSON 字符串，您需要 Agent 类，请参阅下面的完整代码
第二步：你可以用agentDetailsInfoFromJson(response.body);解析

代码sn-p

AgentDetailsInfo agentDetailsInfoFromJson(String str) =>
    AgentDetailsInfo.fromJson(json.decode(str));
...
class AgentDetailsInfo {
  AgentDetailsInfo({
    this.agent,
    this.tenants,
  });

  Agent agent;
  List<Tenantdetails> tenants;
...  
class Agent {
  Agent({
    this.agentName,
    this.agentPhone,
    this.email,
  });

  String agentName;
  String agentPhone;
  String email;  

工作演示

完整代码

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

AgentDetailsInfo agentDetailsInfoFromJson(String str) =>
    AgentDetailsInfo.fromJson(json.decode(str));

String agentDetailsInfoToJson(AgentDetailsInfo data) =>
    json.encode(data.toJson());

class AgentDetailsInfo {
  AgentDetailsInfo({
    this.agent,
    this.tenants,
  });

  Agent agent;
  List<Tenantdetails> tenants;

  factory AgentDetailsInfo.fromJson(Map<String, dynamic> json) =>
      AgentDetailsInfo(
        agent: Agent.fromJson(json["agent"]),
        tenants: List<Tenantdetails>.from(
            json["tenants"].map((x) => Tenantdetails.fromJson(x))),
      );

  Map<String, dynamic> toJson() => {
        "agent": agent.toJson(),
        "tenants": List<dynamic>.from(tenants.map((x) => x.toJson())),
      };
}

class Agent {
  Agent({
    this.agentName,
    this.agentPhone,
    this.email,
  });

  String agentName;
  String agentPhone;
  String email;

  factory Agent.fromJson(Map<String, dynamic> json) => Agent(
        agentName: json["agent_name"],
        agentPhone: json["agent_phone"],
        email: json["email"],
      );

  Map<String, dynamic> toJson() => {
        "agent_name": agentName,
        "agent_phone": agentPhone,
        "email": email,
      };
}

class Tenantdetails {
  Tenantdetails({
    this.entityId,
    this.userId,
  });

  String entityId;
  String userId;

  factory Tenantdetails.fromJson(Map<String, dynamic> json) => Tenantdetails(
        entityId: json["entity_id"],
        userId: json["user_id"],
      );

  Map<String, dynamic> toJson() => {
        "entity_id": entityId,
        "user_id": userId,
      };
}

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> {
  Function _future;

  Future<AgentDetailsInfo> getAgentDetails(String agentId) async {
    print(agentId);
    /*String tokenKey = await SharedPrefUtils.readPrefStr("token");
    String url = Constants.BASEURL + Constants.KEYWORD_GET_AGENT_DETAILS + agentId;
    final response = await http.get(
      url,
      headers: {"Accept": "application/json", "Authorization": tokenKey},
    );*/

    String jsonString = '''
    {  
  "agent":{
    "agent_name": "Shamsudheen",
    "agent_phone": "0581476710",
    "email": "shamsu@gmail.com"
          },
   "tenants": [
    {
        "entity_id": "152",
        "user_id": "37"
    },
    {
        "entity_id": "153",
        "user_id": "37"
    },
    {
        "entity_id": "150",
        "user_id": "37"
    }
 ]
}
    ''';

    http.Response response = http.Response(jsonString, 200);
    if (response.statusCode == 200) {
      return agentDetailsInfoFromJson(response.body);
    }
  }

  @override
  void initState() {
    _future = getAgentDetails;
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: FutureBuilder(
            future: _future("test"),
            builder: (context, AsyncSnapshot<AgentDetailsInfo> snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.none:
                  return Text('none');
                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.tenants.length,
                        itemBuilder: (context, index) {
                          return Card(
                              elevation: 6.0,
                              child: Padding(
                                padding: const EdgeInsets.only(
                                    top: 6.0,
                                    bottom: 6.0,
                                    left: 8.0,
                                    right: 8.0),
                                child: Row(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: <Widget>[
                                    Text(snapshot.data.agent.agentName
                                        .toString()),
                                    Spacer(),
                                    Text(snapshot.data.tenants[index].userId
                                        .toString()),
                                    Spacer(),
                                    Text(snapshot.data.tenants[index].entityId),
                                  ],
                                ),
                              ));
                        });
                  }
              }
            }));
  }
}