angular - 无法处理动画-返回零元素

为数据创建服务后，动画便停止工作。看起来是因为最初加载页面时ng-repeat中没有任何元素(因为它正在获取数据)。似乎与THIS和THIS类似:

错误:

ERROR Error: Unable to process animations due to the following failed trigger transitions @listAnimation has failed due to:

- `query(":enter")` returned zero elements. (Use `query(":enter", { optional: true })` if you wish to allow this.)

动画片:

trigger('listAnimation', [
      transition('* => *', [
        query(':enter', style({ opacity: 0}), { optional: true }),
        query(':enter', stagger('150ms', [
          animate('.5s ease-in', keyframes([
            style({ opacity: 0, /*transform: 'translateY(-75px)',*/ offest: 0}),
            style({ opacity: .5, /*transform: 'translateY(35px)',*/ offest: .3}),
            style({ opacity: 1, /*transform: 'translateY(0px)',*/ offest: 1})
          ]))
        ]))
      ])
    ])

HTML:

<div [@listAnimation]>
    <div *ngFor="let member of members" class="member-card">
      member info goes here...
    </div>
</div>

现在，在您说"put in { optional: true } like the error message says"之前...我做到了-它消除了错误消息，但实际上并没有使动画起作用:

trigger('listAnimation', [
      transition('* => *', [
        query(':enter', style({ opacity: 0}), { optional: true }),
        query(':enter', stagger('150ms', [
          animate('.5s ease-in', keyframes([
            style({ opacity: 0, /*transform: 'translateY(-75px)',*/ offest: 0}),
            style({ opacity: .5, /*transform: 'translateY(35px)',*/ offest: .3}),
            style({ opacity: 1, /*transform: 'translateY(0px)',*/ offest: 1})
          ]))
        ]), {optional: true})
      ])
    ])

请记住，所有这些操作在将数据从应用程序组件中删除之前都是可行的。数据在那里，应用程序正常运行，只是此动画不再起作用。

最佳答案

确保仅当members数组不为空时才显示列表容器。这样，仅当列表中有内容时，动画才会触发。

<div [@listAnimation] *ngIf="members.length > 0">
    <div *ngFor="let member of members" class="member-card">
      member info goes here...
    </div>
</div>

关于angular - 无法处理动画-返回零元素，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46352514/