Error: ExpressionChangedAfterItHasBeenCheckedError - ionic-framework

Question

I am trying to set the value of the attendance.studentName using value on ion-input. But I am getting an error.
I want to push the value of the ion-input and ion-select to firebase.
<!-- When I delete the ngModel it works -->
<ion-input disabled="true" value="{{student.name}}" [(ngModel)]="attendance.studentName" > {{student.name}} </ion-input>
<ion-select item-end [ngModel]="attendance.status">
<ion-option value="Present">Present</ion-option>
<ion-option value="Absent">Absent</ion-option>
<ion-option value="Late">Late</ion-option>
</ion-select>
</ion-item>
**EDIT **
I am fetching the value of the input from firebase and i dont want the user to edit it so I disabled it. Then i fetch the input using the ngModel.
Here's my code..
TS
import { Student } from '../../models/students/students.model';
import { Attendance } from '../../models/attendance/attendance.model';
export class CheckAttendancePage {
studentList$: Observable<Student[]>
attendance: Attendance = {
studentName: '',
status: ''
}
constructor(private afDatabase: AngularFireDatabase, private studentsList: StudentListService, private attendanceList: AttendanceListService,
public navCtrl: NavController, public navParams: NavParams) {
this.studentList$ = this.studentsList
.getStudentList()
.snapshotChanges()
.map(
changes => {
return changes.map(c => ({
key: c.payload.key, ...c.payload.val()
}))
}
)
}
addAttendance(attendance: Attendance){
console.log(attendance)
}
HTML

Answer 1

In .ts file need to setup attendance object
attendance:any={'studentName': '', .'status':''}
in constructor you can set this value
this.attendance.studentName = your firbase name
In .html file
<ion-item>
<ion-input disabled="true" [(ngModel)]="attendance.studentName" type="text">
</ion-input>
<ion-select item-end [(ngModel)]="attendance.status">
<ion-option value="Present">Present</ion-option>
<ion-option value="Absent">Absent</ion-option>
<ion-option value="Late">Late</ion-option>
</ion-select>
</ion-item>
Setting value of attendance.studentName in constructor
constructor(private firebaseDB: AngularFireDatabase){
this.firabase= this.firebaseDB.list('/users');// your route
this.attendance.studentName= this.firabase.name;
}
Setting value of attendance.studentName in user define method suppose its name Dbcall
First of all inject public navCtrl: NavController in constructor
Dbcall(){
this.attendance.studentName= database student value
this.navCtrl.setRoot(this.navCtrl.getActive().component);
}