_InternalLinkedHashMap<String, dynamic>\' 不是类型\'Iterable<dynamic>\' 的子类型怎么解决这个问题答案

【问题标题】：_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Iterable<dynamic>' how to solve this problem_InternalLinkedHashMap<String, dynamic>\' 不是类型\'Iterable<dynamic>\' 的子类型怎么解决这个问题
【发布时间】：2022-08-09 15:50:15
【问题描述】：

我正面临这个问题E/flutter (3688): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] 未处理的异常：类型 \'_InternalLinkedHashMap<String, dynamic>\' 不是类型 \'Iterable\' 的子类型我想从 listview builder 中的 api 获取数据。但是这个我不熟悉的例外。怎么解决我不知道。

import \'dart:convert\';

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

import \'package:learning_1ui_6228/utilities/app_colors.dart\';
import \'package:learning_1ui_6228/utilities/helper.dart\';
import \'package:learning_1ui_6228/utilities/widgets/app_line.dart\';

import \'package:learning_1ui_6228/utilities/widgets/list_tile_widget.dart\';

import \'package:learning_1ui_6228/views/nav_pages/profile_page.dart\';
import \'package:http/http.dart\' as http;

import \'../model/UserModel.dart\';

class FirstScreen extends StatefulWidget {
  const FirstScreen({Key? key}) : super(key: key);

  @override
  State<FirstScreen> createState() => _FirstScreenState();
}

class _FirstScreenState extends State<FirstScreen> {
  Future<UserModel>? futureUser;
  TextEditingController textController = TextEditingController();

  // List<UserModel> userList=[];
  @override
  void initState() {
    
    getData();
    super.initState();
  }

List<UserModel> userModelList=[];
Future<List<UserModel>> getData () async {
    final response=await http.get(Uri.parse(\'https://reqres.in/api/users?page=2\'));
    var data = jsonDecode(response.body.toString());
    if(response.statusCode==200){
      for(Map i in data){
        userModelList.add(UserModel.fromJson(data[i]));
      }
      print(\'User Data list ${userModelList}\');
      return userModelList;
    }else {
      return [];
    }

}



  @override
  Widget build(BuildContext context) {
    print(\'user list ModelListdata + $userModelList\');
    return SafeArea(
      child: Scaffold(
        backgroundColor: Color(0xfff8f8fa),
        body: Column(
          children: [
            //1st Section
            Container(
              height: HelperClass.h250,
              decoration: BoxDecoration(
                  gradient: LinearGradient(
                    colors: AppColors.gradientColor,
                  ),
                  borderRadius: BorderRadius.only(
                      bottomRight: Radius.circular(HelperClass.r10),
                      bottomLeft: Radius.circular(HelperClass.r10))),
              child: Column(
                children: <Widget>[
                  //Text and cross button
                  Container(
                    margin: EdgeInsets.only(
                        left: HelperClass.w10,
                        right: HelperClass.w10,
                        top: HelperClass.h20),
                    height: HelperClass.h50,
                    // color: Colors.red,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.start,
                      children: [
                        Container(
                            child: IconButton(
                                onPressed: () {},
                                icon: Icon(
                                  Icons.clear,
                                  color: Colors.white,
                                  size: 30,
                                ))),
                        Expanded(
                          child: Container(
                            margin: EdgeInsets.only(right: 30),
                            alignment: Alignment.center,
                            //  color: Colors.lightBlueAccent,
                            child: Text(
                              \'Search\',
                              style: TextStyle(
                                  fontSize: HelperClass.t25,
                                  fontWeight: FontWeight.bold,
                                  color: Colors.white),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                  SizedBox(
                    height: HelperClass.h25,
                  ),
                  //Search Bar
                  Container(
                    margin: EdgeInsets.only(
                        left: HelperClass.w10, right: HelperClass.w10),
                    //color: Colors.amber,
                    height: HelperClass.h70,
                    width: double.infinity,
                    child: TextField(
                      controller: textController,
                      onChanged: (name) {
                        setState(() {
                         // searchUser(name);
                        });
                      },
                      decoration: InputDecoration(
                        prefix: Icon(
                          Icons.search,
                          size: 26,
                        ),
                        suffix: IconButton(
                          onPressed: () {
                            setState(() {
                              textController.clear();
                              //searchedList = userList;
                            });
                          },
                          icon: Icon(
                            Icons.clear,
                            size: 26,
                          ),
                        ),
                        hintText: \'Search\',
                        border: OutlineInputBorder(
                          borderRadius: BorderRadius.circular(3),
                          borderSide: BorderSide.none,
                        ),
                        filled: true,
                        fillColor: Colors.white,
                      ),
                    ),
                  ),
                ],
              ),
            ),

            // List View
            Expanded(
              child: FutureBuilder(
                future: getData(),
                  builder: (context, snapshot){
                if(snapshot.hasData){
                  return ListView.builder(
                    itemCount: userModelList.length,
                    shrinkWrap: true,
                    itemBuilder: (context, index) {
                      return Padding(
                        padding: EdgeInsets.all(10),
                        child: Column(
                          children: [
                            InkWell(
                              onTap: () {
                                Navigator.push(
                                    context,
                                    MaterialPageRoute(
                                      builder: (context) => ProfilePage(
                                       // userName:snapshot.data!.data![index].firstName??\'\',
                                        userName: userModelList[index].data![index].firstName??\'\',

                                        //followers: snapshot.data!.data![index].id.toString(),
                                        followers: userModelList[index].data![index].id.toString()??\'N/A\',

                                       // address: snapshot.data!.data![index].email.toString(),
                                        address: userModelList[index].data![index].email??\'\',

                                        //following: snapshot.data!.data![index].lastName.toString(),
                                        following: userModelList[index].data![index].lastName,
                                        //imageUrl: snapshot.data!.data![index].avatar.toString(),
                                        imageUrl: userModelList[index].data![index].avatar??\'N/A\',
                                      ),
                                    ));
                              },
                              child: ListTileWidgets(
                                following:userModelList[index].data![index].lastName,
                                address:  userModelList[index].data![index].email??\'\',
                                imageUrl:userModelList[index].data![index].avatar??\'N/A\',
                                name: userModelList[index].data![index].firstName??\'\',
                                followersCount:
                                \'Followers: ${userModelList[index].data![index].lastName}\',
                                iconWidget: Icon(
                                  Icons.person_add_alt_outlined,
                                  color: Colors.red,
                                  size: 25,
                                ),
                              ),
                            ),
                            AppLine(
                                paddingLeft: 10,
                                paddingRight: 10,
                                heightLine: 1,
                                lineColor: Colors.grey),
                          ],
                        ),
                      );
                    },
                  );
                }
                else if (snapshot.hasError) {
                  return Text(\'${snapshot.error}\');
                }

                // By default, show a loading spinner.
                return Center(child: CircularProgressIndicator());
              }),
            ),
          ],
        ),
      ),
    );
  }
}

**这是我的数据模型

import \'dart:convert\';
UserModel userModelFromJson(String str) => UserModel.fromJson(json.decode(str));
String userModelToJson(UserModel data) => json.encode(data.toJson());
class UserModel {
  UserModel({
      this.page, 
      this.perPage, 
      this.total, 
      this.totalPages, 
      this.data, 
      this.support,});

  UserModel.fromJson(dynamic json) {
    page = json[\'page\'];
    perPage = json[\'per_page\'];
    total = json[\'total\'];
    totalPages = json[\'total_pages\'];
    if (json[\'data\'] != null) {
      data = [];
      json[\'data\'].forEach((v) {
        data?.add(Data.fromJson(v));
      });
    }
    support = json[\'support\'] != null ? Support.fromJson(json[\'support\']) : null;
  }
  int? page;
  int? perPage;
  int? total;
  int? totalPages;
  List<Data>? data;
  Support? support;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    map[\'page\'] = page;
    map[\'per_page\'] = perPage;
    map[\'total\'] = total;
    map[\'total_pages\'] = totalPages;
    if (data != null) {
      map[\'data\'] = data?.map((v) => v.toJson()).toList();
    }
    if (support != null) {
      map[\'support\'] = support?.toJson();
    }
    return map;
  }

}

Support supportFromJson(String str) => Support.fromJson(json.decode(str));
String supportToJson(Support data) => json.encode(data.toJson());
class Support {
  Support({
      this.url, 
      this.text,});

  Support.fromJson(dynamic json) {
    url = json[\'url\'];
    text = json[\'text\'];
  }
  String? url;
  String? text;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    map[\'url\'] = url;
    map[\'text\'] = text;
    return map;
  }

}

Data dataFromJson(String str) => Data.fromJson(json.decode(str));
String dataToJson(Data data) => json.encode(data.toJson());
class Data {
  Data({
      this.id, 
      this.email, 
      this.firstName, 
      this.lastName, 
      this.avatar,});

  Data.fromJson(dynamic json) {
    id = json[\'id\'];
    email = json[\'email\'];
    firstName = json[\'first_name\'];
    lastName = json[\'last_name\'];
    avatar = json[\'avatar\'];
  }
  int? id;
  String? email;
  String? firstName;
  String? lastName;
  String? avatar;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    map[\'id\'] = id;
    map[\'email\'] = email;
    map[\'first_name\'] = firstName;
    map[\'last_name\'] = lastName;
    map[\'avatar\'] = avatar;
    return map;
  }

}

这是我的 api 调用https://reqres.in/api/users?page=2

标签： flutter flutter-layout flutter-dependencies

【解决方案1】：

没有测试过，但我认为问题出在这里：

Future<List<UserModel>> getData () async {
    final response=await http.get(Uri.parse('https://reqres.in/api/users?page=2'));
    var data = jsonDecode(response.body.toString());
    if(response.statusCode==200){
      for(Map i in data){
        userModelList.add(UserModel.fromJson(data[i]));
      }
      print('User Data list ${userModelList}');
      return userModelList;
    }else {
      return [];
    }

}

data 是根据响应的映射，不可迭代。换句话说，您不能使用for (var i in data)，因为只有 Iterables 可以以这种格式使用。相反，看起来整个数据都是一个 UserModel，您应该能够将 data 本身解码为一个 UserModel。我在 API 响应中没有看到多个用户。

【讨论】：