从属< material-dropdown-select> [英] Dependent <material-dropdown-select>

问题描述

我想使用[(ngModel)] + (ngModelChange)链接多个<material-dropdown-select>，使它们相互依赖. (因此，请勿使用*ngFor + <material-select-item>.)

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

但是我没有找到如何使这些<material-dropdown-select>依赖的，因此，当父"被更新时，第一个孩子"被更新/重置，然后在选择第一个孩子时，第二个被重置/updated，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()，但是显然，这不是好方法.

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

也许使用ViewChild/ViewChildren，但选项列表未更新?

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

推荐答案

好吧，我终于得到了所需的东西.

Well I finally get what I needed.

我使用@ViewChild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"，就像我必须首先要做的一样:

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<dynamic>不会更新...

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

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