Angular4占位符用于选择

Question

我正在尝试将一个占位符添加到Angular 4上的选择但是无法使其工作,

这是我的代码:

<select name="edit" [(ngModel)]="edit">
        <option [ngValue]="null" disabled [selected]="true"> Please select one option </option>
        <option *ngFor="let select of list" [ngValue]="edit"> {{ select }}</option>
</select>


export class AppComponent  {
  list: any[] = ['1', '2', '3'];
  edit: any;
}

Answer 1

我创造了plunker.希望这会有所帮助.

 <select name="edit" [(ngModel)]="edit">
    <option [ngValue]="undefined" disabled  selected> Please select one option </option>
    <option *ngFor="let select of list" [ngValue]="edit"> {{ select }}</option>
  </select>
export class AppComponent  {
  list: any[] = ['1', '2', '3'];
  edit: any;
}