PrimeNg DropDown-用户无法清除该值 [英] PrimeNg DropDown - User can't clear the value

问题描述

我正在Angular2应用程序中实现primeNg下拉组件.

I'm implementing primeNg dropdown component in my Angular2 application.

<p-dropdown [options]="listCustomers_itm" placeholder="Selezionare" [(ngModel)]="Customer_itm" [ngModelOptions]="{standalone: true}" [style]="{'width':'225px'}" filter="filter"  (onChange)="onCustomerSelect($event.value)">
</p-dropdown>

除一件烦人的事情外，其他一切正常:

All works fine except one annoing thing:

一旦用户选择了一个选项，他将无法清除所选的值 ...

Once time the user has selected an option, he can't clear the selected value...

你能帮我吗?

推荐答案

要解决此问题，我必须为下拉菜单设置一个占位符.我使用的代码如下:

To fix this, I had to set a placeholder for the dropdown. The code I used is something like:

template.html

<p-dropdown ...
            placeholder="Select"
            #dropDownThing></p-dropdown>

<button (click)="onButtonClick()"></button>

component.ts

import { Dropdown } from "primeng/components/dropdown/dropdown";
...
@ViewChild('dropDownThing')
dropDownThing: Dropdown;
...
onButtonClick() {
    this.dropDownThing.value = <someValueNotInTheDropdown'sList>;
}
...

在运行上面的代码 的情况下，当前选择的选项保持选中状态.

When the code above is run without a placeholder, the currently-selected option remains selected.

当上面的代码与占位符一起运行 时，下拉菜单的值将更改为提供的占位符.

When the code above is run with a placeholder, the dropdown's value changes to the provided placeholder.

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