如果ng-content具有内容或空Angular2

Question

我试图了解如何在a ng-content为空时创建if来显示.

<div #contentWrapper [hidden]="isOpen">
    <ng-content ></ng-content>
</div>

<span *ngIf="contentWrapper.childNodes.length == 0">
    <p>Display this if ng-content is empty!</p>
</span>

当内容为空时我尝试使用那个显示数据,但即使信息为空也不会显示<span>标签

谢谢,永远感谢你的帮助.

Answer 1

用children而不是childNodes.Angular为*ngIf* which are counted bychildNodes` 创建注释节点

<div #contentWrapper [hidden]="isOpen">
    <ng-content ></ng-content>
</div>

<span *ngIf="contentWrapper.children.length == 0">
    <p>Display this if ng-content is empty!</p>
</span>  

Plunker的例子