类型“List<dynamic>”不是“List<String>”类型的子类型

Question

我正在从 firebase 获取数据并使用 fromJson 构造函数对其进行覆盖，但它会引发错误。导致的问题是模型中的类别列表，我已经完成了铸造方法，但它仍然无法正常工作。请帮助我，我从 2 天开始就被困在这里。任何解决方案都不适合我

这是个例外

======== Exception caught by widgets library =======================================================
The following _TypeError was thrown building FutureBuilder<DocumentSnapshot>(dirty, state: _FutureBuilderState<DocumentSnapshot>#6cd83):
type 'List<dynamic>' is not a subtype of type 'List<String>'

The relevant error-causing widget was: 
  FutureBuilder<DocumentSnapshot> file:///E:/flutterProject/filmmaker/lib/auth_screens/signUp_screens/worker/signUp_screen14.dart:93:30
When the exception was thrown, this was the stack: 
#0      new UserInfoModel.fromMap (package:filmmaker/resources/models/user_info.dart:88:19)
#1      _SignUpScreen14State._nameCountry.<anonymous closure> (file:///E:/flutterProject/filmmaker/lib/auth_screens/signUp_screens/worker/signUp_screen14.dart:102:46)
#2      _FutureBuilderState.build (package:flutter/src/widgets/async.dart:773:55)
#3      StatefulElement.build (package:flutter/src/widgets/framework.dart:4612:27)
#4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4495:15)
...
====================================================================================================

这是我未来的构建器小部件，我正在从 firestore 获取数据并将其发送到 fromJson 构造函数

Widget get _nameCountry => FutureBuilder<DocumentSnapshot>(
        future: FirebaseRepo.instance.fetchWorkerDataFromDb(),
        builder: (BuildContext context, AsyncSnapshot<dynamic> snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return CircleAvatar(
                radius: 80.0,
              );
            case ConnectionState.done:
              _userInfoModel = UserInfoModel.fromMap(snapshot?.data?.data());
        //      Map<String, dynamic> data = snapshot?.data?.data();
              return Row(
                children: <Widget>[
                  Text('${_userInfoModel.name}, '),
                  Text('${_userInfoModel.country}, '),                ],
              );
            default:
              return Text(
                snapshot.error,
                textAlign: TextAlign.center,
              );
          }
        },
        // child: Row(
        //       children: <Widget>[Text('${_userInfoModel.name} ,'), Text('')],
        //     ),
      );

我的模型函数

class UserInfoModel {
  String uid,
      name,
      email,
      userName,
      status,
      profilePhoto,
      country,
      profileState,
      expert,
      englishProficiency,
      title,
      professionalOverview,
      phoneNo,
      hourlyRate,createdAt;
  bool signUpCheckForEmail;
  List<String> categories, skills, otherLanguages;
  List<Map> education, employment;
  Map companyData,companyContacts;


  UserInfoModel(
      {this.uid,
      this.name,
      this.email,
      this.userName,
      this.status,
      this.profilePhoto,
      this.country,
      this.profileState,
      this.signUpCheckForEmail,
      this.categories,
      this.skills,
      this.expert,
      this.education,
      this.employment,
      this.englishProficiency,
      this.otherLanguages,
      this.title,
      this.professionalOverview,
      this.companyData,
      this.phoneNo,
      this.hourlyRate,
      this.companyContacts,
      this.createdAt});

  Map toMap(UserInfoModel user) {
    var data = Map<String, dynamic>();
    data['uid'] = user.uid;
    data['name'] = user.name;
    data['email'] = user.email;
    data['userName'] = user.userName;
    data['status'] = user.status;
    data['profilePhoto'] = user.profilePhoto;
    data['country'] = user.country;
    data['profileState'] = user.profileState;
    data['signUpCheckForEmails'] = user.signUpCheckForEmail;
    data['categories'] = user.categories;
    data['skills'] = user.skills;
    data['expert'] = user.expert;
    data['education'] = user.education;
    data['employment'] = user.employment;
    data['english proficiency'] = user.englishProficiency;
    data['other languages'] = user.otherLanguages;
    data['professionalOverview'] = user.professionalOverview;
    data['title'] = user.title;
    data['companyData'] = user.companyData;
    data['phoneNo'] = user.phoneNo;
    data['hourlyRate'] = user.hourlyRate;
    data['companyContacts'] = user.companyContacts;
    data['createdAt']= user.createdAt;
    return data;
  }

  factory UserInfoModel.fromMap(Map<String, dynamic> data) {
    return UserInfoModel(
      uid: data['uid'],
      name: data['name'],
      email: data['email'],
      userName: data['userName'],
      status: data['status'],
      profilePhoto: data['profilePhoto'],
      country: data['country'],
      profileState: data['profileState'],
      signUpCheckForEmail: data['signUpCheckForEmails'],
      categories: data['categories'].cast<String>(),
      skills: data['skills'],
      expert: data['expert'],
      education: data['education'],
      employment: data['employment'],
      englishProficiency: data['english proficiency'],
      otherLanguages: data['other languages'],
      professionalOverview: data['professionalOverview'],
      title: data['title'],
      companyData: data['companyData'],
      phoneNo: data['phoneNo'],
      hourlyRate: data['hourlyRate'],
      companyContacts: data['companyContacts'],
      createdAt:  data['createdAt'],
    );
  }
}

Answer 1

我用一些虚拟数据运行了你的代码，cast<String> for categories 对我有用。但是，您尚未将演员表添加到 skills 和 otherLanguages。您是否检查了错误的行号？如果问题肯定出在categories，您能否在问题中添加一些示例数据。

Answer 2

尝试将List<String> categories, skills, otherLanguages;替换为动态并移除强制转换

List<dynamic> categories, skills, otherLanguages;