如何在 Xamarin.Forms 中访问列表视图数据模板内的按钮单击？

Question

我有listview 有两个动态操纵的视图label 和button，我正在尝试访问按钮单击以转到按钮单击时的详细信息页面。

下面是我的自定义ViewCell

protected override async void OnAppearing()
{
    listClass.ItemsSource = list;
    listClass.ItemTemplate = new DataTemplate(typeof(ItemTemplateViewCell )); 
}

public class ItemTemplateViewCell : ViewCell
{

    Label NameLbl = new Label();
    StackLayout sLayout = new StackLayout ();
    Button btnViewcell = new Button {Text = "Show class details"};
    public ItemTemplateViewCell()
    {
        NameLbl.SetBinding(Label.TextProperty, "Name");
        sLayout.Children.Add(NameLbl);
        btnViewcell.Clicked += (s, e) =>
        {
            // Navigation.PushAsync(new Home()); //I can not using this line 
            // does not exist in the current context, why cant i navigate to 
            // another page from inside datatemplate in List view
        };
        sLayout.Children.Add(btnViewcell);
        this.View = sLayout;
    }
}

Answer 1

您可以通过构造函数将 Navication 传递给 ViewCell：

    public class ItemTemplateViewCell : ViewCell
    {
        // Navigation Mermber
        INavigation MyNavigation;
        Label NameLbl = new Label();
        StackLayout sLayout = new StackLayout ();
        Button btnViewcell = new Button {Text = "Show class details"};
        public ItemTemplateViewCell(INavigation navigation)
        {
            MyNavigation = navigation;
            NameLbl.SetBinding(Label.TextProperty, "Name");
            sLayout.Children.Add(NameLbl);
            btnViewcell.Clicked += ButtonShowDetails_Clicked;
            sLayout.Children.Add(btnViewcell);
            this.View = sLayout;
        }

        private void ButtonShowDetails_Clicked(object sender, EventArgs e)
        {                                                  
             MyNavigation.PushAsync(new Home());
        }
    }

然后通过委托函数传递导航

    protected override async void OnAppearing()
    {
       listClass.ItemsSource = list;
       listClass.ItemTemplate = new DataTemplate(Function) ; 
    }

    public object Function()
    {
        return new ItemTemplateViewCell (Navigation);
    }

然后就可以访问ViewCell中的Navigation对象了

Answer 2

您只需将CommandParameterProperty 与绑定一起使用即可：

例子：

ListViewClass.ItemTemplate = new DataTemplate(() =>
{
  var GoHomeButton = new Button { Text = "Go Home", HorizontalOptions = LayoutOptions.StartAndExpand };
  GoHomeButton.SetBinding(Button.CommandParameterProperty, new Binding("Name"));
  GoHomeButton.Clicked += Gohome;
//return new view cell 
 }
    private void Gohome(object sender, EventArgs e)
    {      
            Navigation.PushAsync(new Home());
    }

欲了解更多信息，请查看以下链接：

http://www.c-sharpcorner.com/blogs/handling-child-control-event-in-listview-using-xamarinforms1

Answer 3

我认为出错的是你在类的初始化中立即执行了一个动作。你应该像下面这样拆分它。另一个问题是您在方法之外对变量进行初始化。这可能没问题，但我更喜欢下面的代码：

public class ItemTemplateViewCell : ViewCell
{

    Label nameLbl;
    StackLayout sLayout;
    Button btnViewcell;
    public ItemTemplateViewCell()
    {
        nameLbl = new Label()
        sLayout = new StackLayout ()
        btnViewcell = new Button {Text = "Show class details"};

        NameLbl.SetBinding(Label.TextProperty, "Name");
        sLayout.Children.Add(NameLbl);
        btnViewcell.Clicked += OnButtonClicked;
        sLayout.Children.Add(btnViewcell);
        this.View = sLayout;
    }

    void OnButtonClicked(object sender, EventArgs e)
    {
        Navigation.PushAsync(new Home()); 
    }
}

我认为这应该适用于您的情况，但我不能确定。我不认为您发布的内容与您的代码是一对一的，因为我在您的代码中看不到 s 和 e 的任何初始化，并且如 cmets 中所述，如果您真的在代码中的注释会导致问题把它放在问题中。此外，您不共享 Home 类的代码。最后可能有问题。

Answer 4

Navigation 在ViewCell 中不可用，这意味着您无法直接从ViewCell 访问它。但这应该可行：

App.Current.MainPage.Navigation.PushAsync(new Home());

整个代码：

protected override async void OnAppearing()
{
    listClass.ItemsSource = list;
    listClass.ItemTemplate = new DataTemplate(typeof(ItemTemplateViewCell )); 
}

public class ItemTemplateViewCell : ViewCell
{

    Label NameLbl = new Label();
    StackLayout sLayout = new StackLayout ();
    Button btnViewcell = new Button {Text = "Show class details"};
    public ItemTemplateViewCell()
    {
        NameLbl.SetBinding(Label.TextProperty, "Name");
        sLayout.Children.Add(NameLbl);
        btnViewcell.Clicked += (s, e) =>
        {
            App.Current.MainPage.Navigation.PushAsync(new Home());
        };
        sLayout.Children.Add(btnViewcell);
        this.View = sLayout;
    }
}