我有一个搜索栏和一个元素列表的模态，创建了一个ngbDropdown拆分成2个组件，父和子.它工作正常，但我不能想出一种方法来启用键盘导航（使用向上和向下键在列表的元素之间移动）.
按照官方文档，我尝试使用ngbDropdownItem，但它不工作.
以下是我的2个组件的模板：
1.母体：

<div ngbDropdown class="dropdown-no-arrow" (openChange)="openChange($event)" container="body">

  <!-- trigger -->
  <ng-container>
    <button class="btn" ngbDropdownToggle *ngIf="authorizationService.loggedInUser">
      <i class="fal fa-farm me-2"></i>
      <span>{{ authorizationService.loggedInUser.name }}</span>
      <i class="fal fa-chevron-down ms-2"></i>
    </button>
  </ng-container>

  <!-- menu -->
  <div ngbDropdownMenu aria-labelledby="currentMenuItem" id="currentDropdown_{{ id }}">
    
    <button ngbDropdownItem (click)="openNewModal()">
      <i class="fal fa-plus me-1"></i> <span i18n>New</span>
    </button>

    <dm-child-list [isListDisplayed]="isDropdownOpened"></dm-child-list>
  </div>
</div>

1.孩子：

<div class="dropdown-header d-flex margin-x align-items-center">
  <h6 class=" mb-0 flex-grow-1" i18n>MY LIST</h6>
</div>
<div class="px-4 py-2">
  <div class="form-group mb-0">
    <input class="form-control form-control-sm" libAutofocus [(ngModel)]="elSearch" (ngModelChange)="elSearch$.next($event)" i18n-placeholder placeholder="Search elements">
  </div>
</div>

<button *ngFor="let el of list; let i = index;" ngbDropdownItem [ngClass]="{'top-border': i === 0}">
  <i class="me-2 fas fa-check-circle text-success"
     *ngIf="selectedEl?.id === el.id" title="Current element"></i>
  <i class="me-2 fal fa-circle" *ngIf="selectedEl?.id !== el.id"></i>
  <span>{{ el.name }}</span>
</button>

有谁能帮我实现键盘选择吗？
谢谢!