如何从角度4预选下拉值

Question

我有一个下拉列表。

 <select class="form-control" [(ngModel)]="UpdateTeacher.TeacherId" name="TeacherName" value={{UpdateTeacher.TeacherId}} required #TeacherName="ngModel">
          <option *ngFor="let TeacherDetail of this.userService.TeacherDetails" value="{{TeacherDetail.TeacherId}}">
            {{TeacherDetail.TeacherName}} </option>
 </select>

现在this.userService.TeacherDetails是我正在迭代的一个Teacher对象数组。我已经在UpdateTeacher.TeacherId中设置了一个值为2当显示下拉2选项时必须预选。怎么实现呢？ 提前致谢。

Answer 1

值应写为输入sig(df) df pos [1,] 1 0 [2,] 2 0 [3,] 3 0 [4,] 4 4 [5,] 5 5 [6,] 6 6 [7,] 7 7 [8,] 8 8 [9,] 9 9 [10,] 10 10

即

[value]="something"

Answer 2

      <select class="form-control" [(ngModel)]="UpdateTeacher.TeacherId" name="TeacherName" value={{UpdateTeacher.TeacherName}} required
      #TeacherName="ngModel">
      <option *ngFor="let TeacherDetail of this.userService.TeacherDetails" selected="{{UpdateTeacher.TeacherId == TeacherDetail.TeacherId}}"
        value="{{TeacherDetail.TeacherId}}">
        {{TeacherDetail.TeacherName}} </option>
    </select>