Angular Material Select，selectionChange 未触发

Question

我准备了示例( Angular Material 选择):

Stackblitz

I have set value on ngOnInIt for mat-select, but selectionChange event isnot firing. Whenever I set value to mat-select with value property, I want thatselectionChange is fired, and I want to do some work onselectionChange.

selectionChange 在用户手动选择时触发，但在设置值时不触发。

为什么 selectionChange 事件没有触发？

是否有任何其他事件或方法可以实现此目标？

Answer 1

Demo selectionChange 事件仅在用户更改 html 元素而不是后端数据更改时触发。您可以使用 Viewchild 作为手动调用函数的方式:

@ViewChild("changeEl") el!: ElementRef;

    ngAfterViewInit(){
        this.selectedFood = this.foods[0].value;
        this.selectionChangeTax(this.el)
      }

HTML:

<h4>Basic mat-select</h4>
<mat-form-field appearance="fill">
  <mat-label>Favorite food</mat-label>
  <mat-select (selectionChange)="selectionChangeTax($event)" #changeEl [(value)]="selectedFood">
    <mat-option *ngFor="let food of foods" [value]="food.value">
      {{food.viewValue}}
    </mat-option>
  </mat-select>
</mat-form-field>