相关的<material-dropdown-select> [英] Dependent <material-dropdown-select>

问题描述

我想链接多个，使用[(ngModel)] + (ngModelChange)，使得他们依赖.(所以不能使用 *ngFor + .)

I want to link multiple <material-dropdown-select>, using [(ngModel)] + (ngModelChange), making them dependent. (So not by using *ngFor + <material-select-item>.)

但我没有找到如何使这些 <material-dropdown-select> 依赖，这样当父"被更新时，第一个孩子"被更新/重置，并且然后当第一个孩子被选中时，第二个被重置/更新，依此类推.

But I do not find how to make these <material-dropdown-select> dependent, such that when the "parent" is updated, the "first child" is updated/reset, and then when the first child is selected, the second is reset/updated, and so on.

我尝试过 querySelector() 但显然，这不是好方法.

I tried with querySelector() but obviously, this is not the good way.

也许使用 ViewChild/ViewChildren 但选项列表没有更新???

Maybe with ViewChild/ViewChildren but the options list is not updated???

推荐答案

好吧，我终于得到了我需要的东西.

Well I finally get what I needed.

我使用 @ViewChild 来定位页面中的元素.

I used @ViewChild to target the element in the page.

但是更改选项很棘手"，因为我必须首先:

But changing the options "was tricky", as I had to first :

• MaterialDropdownSelectComponent.options.dispose();

然后

• 添加新列表...

没有第一步，SelectionOptions 不会更新...

without the first step, the SelectionOptions<dynamic> is not updated…

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