Angular 材质：当值为 null 时，在初始页面加载时在 Mat-Select 中显示空选项（无）

Question

Need to display the empty (None) option in Material Select element when the item is null.

    <mat-label>Status</mat-label>
    <mat-select formControlName="statusId">

        <mat-option>None</mat-option>

        <mat-option *ngFor="let item of statuses" [value]="item.id">
             {{ item.name }}
        </mat-option>
    </mat-select>
</mat-form-field>```

As seen in above snippet I need to display the "None" option selected by default when the page loads.

Answer 1

StackBlitz So, you can add a empty value to the None option.

 <mat-select [formControl]="foodControl" name="food">
      <mat-option value="">None</mat-option>
      <mat-option *ngFor="let food of foods" [value]="food.value">
        {{food.viewValue}}
      </mat-option>
    </mat-select>

And, in the ts, you can initialize the control with empty value like this foodControl = new FormControl('');

same thing can be done with ngModel as well. (included in the StackBlitz)