Question

我正在创建自己的UserControl，我在XAML的 UserControl.Resources 部分下有两个不同的DataTemplates。我想在这两个datatemplates之间进行选择，具体取决于listview中显示的对象的属性值。我这样做是通过创建一个自定义的 DataTemplateSelector 类并重写 SelectTemplate 方法，该方法应该返回我想要使用的DataTemplate。但是，我不知道如何“找到”位于UserControls资源部分的数据模板，我看到的所有示例只从 Window.Resources 获取数据模板。在此示例中，他们获取当前的 MainWindow ，然后使用 FindResource 查找 DataTemplate ，如何获取 UserControl 以类似的方式？：


public override DataTemplate 
            SelectTemplate(object item, DependencyObject container)
        {
            if (item != null && item is AuctionItem)
            {
                AuctionItem auctionItem = item as AuctionItem;
                Window window = Application.Current.MainWindow;

                switch (auctionItem.SpecialFeatures)
                {
                    case SpecialFeatures.None:
                        return 
                            window.FindResource("AuctionItem_None") 
                            as DataTemplate;
                    case SpecialFeatures.Color:
                        return 
                            window.FindResource("AuctionItem_Color") 
                            as DataTemplate;
                }
            }

            return null;
        }

上面的示例来自此处：ItemsControl.ItemTemplateSelector Property

Answer 1

试试这个：

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        if (item != null && item is AuctionItem)
        {
            AuctionItem auctionItem = item as AuctionItem;

            switch (auctionItem.SpecialFeatures)
            {
                case SpecialFeatures.None:
                    return 
                        ((FrameworkElement)container).FindResource("AuctionItem_None") 
                        as DataTemplate;
                case SpecialFeatures.Color:
                    return 
                        ((FrameworkElement)container).FindResource("AuctionItem_Color") 
                        as DataTemplate;
            }
        }

        return null;
    }

Answer 2

我通常使用DataConmplateSelector的构造函数中的UserControl作为参数从代码后面实例化我的DataTemplateSelector，如下所示：

public class MyUserControl : UserControl
{
    public MyUserControl()
    {
        Resources["MyDataTemplateSelector"] = new MyDataTemplateSelector(this);
        InitializeComponent();
    }
}

public class MyDataTemplateSelector : DataTemplateSelector
{
    private MyUserControl parent;
    public MyDataTemplateSelector(MyUserControl parent)
    {
        this.parent = parent;
    }

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        parent.DoStuff();
    }
}

不是镇上最漂亮的女孩，但它完成了工作;）

希望这有帮助！

Answer 3

       <DataTemplate x:Key="addTemplate">
        <Button Command="{Binding Path=AddCommand}">Add</Button>
    </DataTemplate>

    <DataTemplate x:Key="editTemplate">
        <Button Command="{Binding Path=UpdateCommand}">Update</Button>
    </DataTemplate>

    <TemplateSelectors:AddEditTemplateSelector
        AddTemplate="{StaticResource addTemplate}"
        EditTemplate="{StaticResource editTemplate}"
        x:Key="addEditTemplateSelector" />

仅限XAML！

Answer 4

WinRT＆amp; Windows Phone解决方案涉及向上移动可视树，直到找到父控件：

    protected override Windows.UI.Xaml.DataTemplate SelectTemplateCore(object item, Windows.UI.Xaml.DependencyObject container)
    {
        var parent = FindParent<MyParentControlType>(container as FrameworkElement);

        if(parent != null)
        {
            if (item is Something)
                return parent.Resources["TemplateForSomething"] as DataTemplate;
            else if(item is SomethingElse)
                return parent.Resources["TemplateForSomethingElse"] as DataTemplate;
            else 
                // etc
        }
        else
        {
            return App.Current.Resources["SomeFallbackResource"] as DataTemplate;
        }
    }

    public static T FindParent<T>(FrameworkElement element) where T : FrameworkElement
    {
        FrameworkElement parent = Windows.UI.Xaml.Media.VisualTreeHelper.GetParent(element) as FrameworkElement;

        while (parent != null)
        {
            T correctlyTyped = parent as T;

            if (correctlyTyped != null)
                return correctlyTyped;
            else
                return FindParent<T>(parent);
        }

        return null;
    }

FindParent方法基于此处接受的答案：How to get a ListView from a ListViewItem?

如何在WPF中的DataTemplateSelector类中查找UserControl中的资源？

4 个答案: