Nativescript开关不触发初始绑定

问题描述

我的观点是

<Switch checked="{{ active }}" propertyChange="onCheckChange"/>

exports.onCheckChange = function(args)
{
   //Api Service call
}

实际上，我是通过API调用绑定活动值的，而问题是onCheckChange在初始绑定期间以假值执行，因此每当我最初通过api服务调用设置active==true并加载页面时，onCheckChange用checked==false执行，任何人都可以给我一个想法.

Actually I am binding the active value by API call and the issue is that onCheckChange gets executed during the initial binding with false value, so whenever I initially set the active==true by api service call and load the page, the onCheckChange is executed with checked==false, can anyone give me an idea about this please.

注意:Nativescript的初学者

推荐答案

双向数据绑定(由leoncc描述)可能特定于 Angular NativeScript.

The two-way data-binding (described by leoncc) might be specific to the Angular NativeScript.

这是一种没有双向数据绑定的解决方法，希望如果需要的话，可以更轻松地移植到 plain NativeScript.

Here's a workaround without the two-way data binding, hopefully it will be easier to port to the plain NativeScript if needs be.

在控制器中，我们可以通过ViewChild查询获取Switch的状态:

In the controller we can get the state of the Switch with a ViewChild query:

  checked = true;
  @ViewChild ('switch') private switch: ElementRef;
  switched() {
    let switch: Switch = this.switch.nativeElement;
    this.checked = switch.checked}

在模板中，我们应该调用switched更改处理程序:

And in the template we should invoke the switched change handler:

<Switch #switch [checked]="checked" (checkedChange)="switched()" class="switch"></Switch>

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