单击选项卡时如何在TabbedPage中加载数据? [英] How to load data in TabbedPage when a tab is clicked?

问题描述

我正在使用TabbedPage进行标签导航.我所有的Page类都只有一个空的默认构造函数，我将数据加载到OnAppearing方法中.我有5个标签.当我单击第二个选项卡时，也会调用第三，第四和第五页的OnAppearing方法.

I am using TabbedPage for navigation with tabs. All my Page classes have just an empty default constructor and I load my data in the OnAppearing method. I have 5 tabs. As soon as I click on the second tab, the OnAppearing methods of the 3rd, 4th and 5th pages are also called.

如何确保仅在单击选项卡时才加载数据?

How do I ensure that the data is only loaded when I click on the tab?

推荐答案

解决方案:

您可以在方法OnCurrentPageChanged中获取currentPage的索引，如果索引等于1(第二页)，请使用messagecenter将消息发送到该页面.请参考以下代码.

You can get the index of currentPage in method OnCurrentPageChanged And if the index equals 1(second page) , use the messagecenter to send message to the page.Refer the following code .

在标签页中

in Tabbed Page

protected override void OnCurrentPageChanged()
{
   base.OnCurrentPageChanged();

   int index = Children.IndexOf(CurrentPage);

   if (index == 1)
   {
      MessagingCenter.Send<Object>(this, "click_second_tab");
   }

   else if (index == 2)
   {
      MessagingCenter.Send<Object>(this, "click_third_tab");
   }


} 

在第二页中.将将数据从onAppearing加载到构造函数中的代码

in the second page .Move the code that load data from onAppearing to the constructor

public MyPage1()
{

  //...
  MessagingCenter.Subscribe<Object>(this, "click_second_tab", (obj) =>
  {
     //load your data here

      Console.WriteLine("11111");
  });

} 

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