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android - 未处理的异常：“int”类型不是“String”类型的子类型

问题描述

干杯，我正在尝试从 UI 中获取 TextField 值，将它们放入地图中，然后在每次单击考试创建屏幕中的“创建”按钮时将该地图放入“考试”集合中，我收到错误 [错误：颤振/lib/ui/ui_dart_state.cc(186)] 未处理的异常：“int”类型不是“String”类型的子类型，该文档未添加到 Firebase 集合中，并且未显示下一个屏幕，以下是有问题的文件：

CreateExam 文件

class CreatExam extends StatefulWidget {


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

class _CreatExamState extends State<CreatExam> {

final _formKey = GlobalKey<FormState>();
DateTime  pickedDate;
TimeOfDay pickedTime;
DatabaseService db= DatabaseService();
String title;
String examID;
Timestamp deadline;
double globalScore;
double duration;
bool _isLoading=false;

void initState(){
super.initState();
pickedDate=DateTime.now();
pickedTime=TimeOfDay.now();
}
@override
Widget build(BuildContext context) {
 
 return SafeArea(
   
       child: Scaffold(
         backgroundColor: Colors.blue[100],

         appBar: AppBar(
           backgroundColor: Colors.blue[100],
           elevation: 0,
           title: Text("Create Exam",style: TextStyle(color: Colors.black),),
           centerTitle: true,
           leading: IconButton(
           onPressed: (){
        Navigator.pushNamed(context, '/ProfessorHomePage');
          },
      icon: Icon(Icons.arrow_back_ios),
      color: Colors.black,
      ),
         ),

   body: _isLoading ? Container (
     child:Center(child: CircularProgressIndicator(),) ,
   ) :Form(
     key: _formKey,
       child: Container(
         padding: EdgeInsets.all(20),
         child: SingleChildScrollView(
                       child: Column(
             children: <Widget>[
               
             TextFormField(
             validator: (val) => val.isEmpty ? "Enter Exam title please" : null,
             decoration: InputDecoration(
               hintText: "Exam Title",
               fillColor: Colors.white,
               filled: true,
             ),
             onChanged: (val){title=val;},
           ),
           SizedBox(height:20),
           TextFormField(
             validator: (val) => val.isEmpty ? "Enter Exam duration please" : 60,
             decoration: InputDecoration(
               hintText: "Exam Duration (minutes)",
               fillColor: Colors.white,
               filled: true,
             ),
             onChanged: (val){duration=double.parse(val);},
           ),
           SizedBox(height:20),
           TextFormField(
             validator: (val) => val.isEmpty ? "Enter Exam Global Score please" : null,
             decoration: InputDecoration(
               hintText: "Global Score",
               fillColor: Colors.white,
               filled: true,
             ),
             onChanged: (val){globalScore=double.parse(val);},
           ),
           SizedBox(height:20),
           Container(
             color: Colors.white,
              child: ListTile(
               title:Text("Date limite : ${pickedDate.year} / ${pickedDate.month} / ${pickedDate.day}"),
               trailing: Icon(Icons.calendar_today),
               onTap: _pickDate,
             ),
           ),
           SizedBox(height:20),
           Container(
             color: Colors.white,
              child: ListTile(
               title:Text("Heure limite : ${pickedTime.hour} : ${pickedTime.minute} "),
               trailing: Icon(Icons.lock_clock),
               onTap: _pickTime,
             ),
           ),
           SizedBox(height:20),
           Container(
             width: MediaQuery.of(context).size.width/2,
             decoration: BoxDecoration(
               borderRadius: BorderRadius.circular(20),
               color: Colors.white,
             ),
             
             child: TextButton(
               onPressed: (){createExam();}, 
               child: Text("Create",style:TextStyle(fontSize: 18,color: Colors.black) ,)
               )
             )
       ],
       ),
         ),
       
     ),
   ),
   ),
 );
}
_pickDate() async {
 DateTime date = await showDatePicker(context: context, initialDate: DateTime.now(), firstDate: DateTime.now(), lastDate: DateTime(2025));
 if(date!=null){
   setState(() {
     pickedDate=date;
   });
 }
}

_pickTime() async {
 TimeOfDay time = await showTimePicker(context: context, initialTime: TimeOfDay.now());
 if(time!=null){
   setState(() {
     pickedTime=time;
   });
 }
}

createExam() async {
 if(_formKey.currentState.validate()){
   setState(() {
     _isLoading=true;
   });
     var uuid=Uuid();
      examID=uuid.v1().toString();
     DateTime time = DateTime(pickedDate.year,pickedDate.month,pickedDate.day,pickedTime.hour,pickedTime.minute);
     Timestamp date = Timestamp.fromDate(time);
     
     
     Map<String,dynamic> examMap ={
       "examID":examID,
       "duration":duration,
       "title":title,
       "deadline":date,
       "globalscore":globalScore,
     };

     await db.addExamToFirebase(examMap, examID).then((value){
       setState(() {
         _isLoading=false;
         Navigator.of(context).pushReplacement(MaterialPageRoute(builder:(context)=> CreateQuestions(examID)));
       
       });
     });
 }
}
}

数据库文件

class DatabaseService {
  final String uid;
  DatabaseService({this.uid});

  //collection reference.
  final CollectionReference usersCollection =
      FirebaseFirestore.instance.collection('users');
  final CollectionReference classroomsCollection =
      FirebaseFirestore.instance.collection('classrooms');
  final CollectionReference examsCOllection =
      FirebaseFirestore.instance.collection("exams");
  
  
  //The functions that will update the infos of the user.
  Future updateUserData(
      {String name,
      String lastName,
      String email,
      String password,
      String pfpPath,
      String userName,
      String role,
      List classesList}) async {
    return await usersCollection.doc(uid).set({
      'name': name,
      'lastname': lastName,
      'email': email,
      'password': password,
      'pfpPath': pfpPath,
      'username': userName,
      'role': role,
      'classeslist': classesList
    });
  }
  // add to classes List in firebase
   Future updateUserClasses(List classesList) async{
     return await usersCollection.doc(uid).set({'classeslist':classesList});
   }

Future addToUserClassesList(CustomClass classroom) async {
    var userData = await usersCollection.doc(uid).get();
    var list = userData.get('classeslist');
    list.add(classroom);
    await updateUserClasses(list);
 
}
  //user data from snapshot.
  CustomUser userDataFromSnapshot(DocumentSnapshot snapshot) {
    CustomUser customUser = CustomUser();
    customUser.setName = snapshot.get('name');
    customUser.setLastName = snapshot.get('lastname');
    customUser.setEmail = snapshot.get('email');
    customUser.setPassword = snapshot.get('password');
    customUser.setPfpPath = snapshot.get('pfpPath');
    customUser.setUserName = snapshot.get('username');
    customUser.setRole = snapshot.get('role');
    customUser.setClassesList = snapshot.get('classeslist');
    return customUser;
  }

  //user doc stream.
  Stream<CustomUser> get customUserData {
    return usersCollection.doc(uid).snapshots().map(userDataFromSnapshot);
  }

  // function for class creation in firebase
  Future addClassroomToFirebase(String name,String subject,String password,String classID) async {

      Map<String,dynamic> classroomInfo = {
        "name":name,
        "subject":subject,
        "classID" : classID,
        "classPassword":password,
        "studentIDList":[]
      };
     return await classroomsCollection.add(classroomInfo);
}

  
  
  //methode to fetch the class id

  Future fetchID(String id) async {
    classroomsCollection.snapshots().listen((snapshot) { 
      snapshot.docs.forEach((doc) { 
        if(id==doc.get("classID")){
          return doc.id;
        }
      });
    });
  }

 //get classrooms stream

 Stream<QuerySnapshot> get classrooms {
   return classroomsCollection.snapshots();
 }

 //upload Exam to firebase

 Future addExamToFirebase(Map examData, String examID) async {
   examsCOllection.doc(examID).set(examData)
   .catchError((e){
     print(e.toString());
   });
 }

 //upload Questions to firebase

 Future addQuestionstoFirebase(Map questionData, String examID) async {
   await examsCOllection.doc(examID).collection("question").add(questionData);

 }

}

这是调试控制台内容：

    I/ViewRootImpl@99756eb[MainActivity]( 3207): ViewPostIme pointer 0
I/ViewRootImpl@99756eb[MainActivity]( 3207): ViewPostIme pointer 1
E/flutter ( 3207): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: type 'int' is not a subtype of type 'String'
E/flutter ( 3207): #0      _CreatExamState.build.<anonymous closure>
E/flutter ( 3207): #1      FormFieldState._validate
E/flutter ( 3207): #2      FormFieldState.validate.<anonymous closure>
E/flutter ( 3207): #3      State.setState
E/flutter ( 3207): #4      FormFieldState.validate
E/flutter ( 3207): #5      FormState._validate
E/flutter ( 3207): #6      FormState.validate
E/flutter ( 3207): #7      _CreatExamState.createExam
E/flutter ( 3207): #8      _CreatExamState.build.<anonymous closure>
E/flutter ( 3207): #9      _InkResponseState._handleTap
E/flutter ( 3207): #10     GestureRecognizer.invokeCallback
E/flutter ( 3207): #11     TapGestureRecognizer.handleTapUp
E/flutter ( 3207): #12     BaseTapGestureRecognizer._checkUp
E/flutter ( 3207): #13     BaseTapGestureRecognizer.acceptGesture
E/flutter ( 3207): #14     GestureArenaManager.sweep
E/flutter ( 3207): #15     GestureBinding.handleEvent
E/flutter ( 3207): #16     GestureBinding.dispatchEvent
E/flutter ( 3207): #17     RendererBinding.dispatchEvent
E/flutter ( 3207): #18     GestureBinding._handlePointerEventImmediately
E/flutter ( 3207): #19     GestureBinding.handlePointerEvent
E/flutter ( 3207): #20     GestureBinding._flushPointerEventQueue
E/flutter ( 3207): #21     GestureBinding._handlePointerDataPacket
E/flutter ( 3207): #22     _rootRunUnary (dart:async/zone.dart:1370:13)
E/flutter ( 3207): #23     _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter ( 3207): #24     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1170:7)
E/flutter ( 3207): #25     _invoke1 (dart:ui/hooks.dart:180:10)
E/flutter ( 3207): #26     PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:276:7)
E/flutter ( 3207): #27     _dispatchPointerDataPacket (dart:ui/hooks.dart:96:31)
E/flutter ( 3207):

标签： androidfirebaseflutterdartgoogle-cloud-firestore

解决方案

当出现类型异常时，只需检查代码中是否存在错误的类型断言。检查这是否导致错误，验证器必须返回 a Stringornull而您返回60的是 a int。尝试更改60to"60"并判断它是否有效：

TextFormField(
             validator: (val) => val.isEmpty ? "Enter Exam duration please" : "60",
             decoration: InputDecoration(
               hintText: "Exam Duration (minutes)",
               fillColor: Colors.white,
               filled: true,
             ),
             onChanged: (val){duration=double.parse(val);},
           ),

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