Question

当子菜单项路由激活时，我想打开paren mat-menu。

组件html

 <li>
     <a #open_business="matMenuTrigger" [matMenuTriggerFor]="menu_business" routerLinkActive="active-list-item"
         routerLink="/admin/business" [ngClass]="'hasClild'">
     </a>
     <mat-menu class="dropdown-toggle waves-light" #menu_business="matMenu" yPosition="below">
         <ul>
             <li class="dropdown-item"><a routerLinkActive="active-list-item"
                     routerLink="/admin/business/business1">business1</a></li>
             <li class="dropdown-item"><a routerLinkActive="active-list-item"
                     routerLink="/admin/business/business2">business2</a></li>
         </ul>
     </mat-menu>
 </li>

在组件ts

中

  @ViewChild('open_user',{static: false}) open_user : MatMenuTrigger
  @ViewChild('open_business',{static: false}) open_business : MatMenuTrigger

.
.
.

  ngAfterViewChecked(){
    if(this.router.url.match(/business/g)){
      this.open_business.openMenu()
    }
     ....

  }

，上面的代码返回以下错误。同样也不允许其他动作。

_MatMenu.html:1 ERROR Error: ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked. Previous value: '@transformMenu: void'. Current value: '@transformMenu: enter'.

如何保持子菜单项（active-list-item）上的父菜单打开？

0 个答案: