wpf - 仅调用ContentTemplateSelector一次，以显示始终相同的数据模板

Question

我制作了一个VS 2010 RC样本示例演示项目，因为在我的生产项目中，使用MVVM时遇到相同的错误。

在我的示例演示项目中，我仅使用无第三方依赖的Code-behind，因此您可以在此处下载演示项目并自己运行:http://www.sendspace.com/file/mwx7wv

现在解决问题:当我单击女孩/男孩按钮时，应该切换数据模板，不是吗？

我怎么了

好的，我也在这里提供了一个代码段:

MainWindow.cs背后的代码:

namespace ContentTemplateSelectorDemo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        Person person;

        public MainWindow()
        {
            InitializeComponent();

            person = new Person(){ Gender = "xxx"};
            person.IsBoy = true;    

            ContentGrid.DataContext = person;
        }

        private void btnBoys_Click(object sender, RoutedEventArgs e)
        {
            person.IsBoy = true;
            person.IsGirl = false;
            this.ContentGrid.DataContext = person;
        }

        private void btnGirls_Click(object sender, RoutedEventArgs e)
        {
            person.IsGirl = true;
            person.IsBoy = false;
            this.ContentGrid.DataContext = person;    
        }        
    }
}

XAML MainWindow.xaml:

<Window x:Class="ContentTemplateSelectorDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:ContentTemplateSelectorDemo"
        Title="MainWindow" Height="350" Width="525">

    <Window.Resources>            
        <DataTemplate x:Key="girlsViewTemplate">
            <local:UserControl1 />
        </DataTemplate>

        <DataTemplate x:Key="boysViewTemplate" >
            <local:UserControl2 />
        </DataTemplate>

        <local:PersonDataTemplateSelector x:Key="PersonSelector" />            
    </Window.Resources>

    <Grid x:Name="ContentGrid" >
        <StackPanel>
            <Button Name="btnGirls" Click="btnGirls_Click">Switch Girls</Button>
            <Button Name="btnBoys" Click="btnBoys_Click">Switch Boys</Button>
        <ContentControl Content="{Binding}" ContentTemplateSelector="{StaticResource ResourceKey=PersonSelector}" />
        </StackPanel>
    </Grid>
</Window>

DataTemplateSelector类:

public class PersonDataTemplateSelector : DataTemplateSelector
{
    public override DataTemplate SelectTemplate(object item,DependencyObject container)
    {
        if (item is Person)
        {
            Person person = item as Person;

            Window window = Application.Current.MainWindow;

            if (System.ComponentModel.DesignerProperties.GetIsInDesignMode( window))
                return null;

            if (person.IsBoy)               
                return window.FindResource("boysViewTemplate") as DataTemplate;
            if (person.IsGirl)            
                return window.FindResource("girlsViewTemplate") as DataTemplate;

        }
        return null;
    }
}

:)

Answer 1

我喜欢Neil的解决方案(可通过Josh's post在the link you provided上找到):

<DataTemplate DataType="{x:Type local:MyType}">
    <ContentPresenter Content="{Binding}" Name="cp" />
    <DataTemplate.Triggers>
        <DataTrigger Binding="{Binding Path=IsRunning}" Value="True">
            <Setter TargetName="cp" Property="ContentTemplate" Value="{StaticResource StopTemplate}" />
        </DataTrigger>
        <DataTrigger Binding="{Binding Path=IsRunning}" Value="False">
            <Setter TargetName="cp" Property="ContentTemplate" Value="{StaticResource StartTemplate}" />
        </DataTrigger>
    </DataTemplate.Triggers>
</DataTemplate>

编辑:我实际上无法使上面的代码正常工作，但是使用一种样式可以工作:

<ContentControl DockPanel.Dock="Bottom" >
    <ContentControl.Style>
        <Style>      
            <Style.Triggers> 
                <DataTrigger Binding="{Binding Path=SourceSystem.SourceSystemName}" Value="mysite.com">
                    <Setter Property="ContentControl.ContentTemplate" Value="{StaticResource mysiteToolbar}" />
                </DataTrigger>

                <DataTrigger Binding="{Binding Path=SourceSystem.SourceSystemName}" Value="mysite2.com">
                    <Setter Property="ContentControl.ContentTemplate" Value="{StaticResource mysiteToolbar2}" />
                </DataTrigger>
            </Style.Triggers>            
        </Style>
    </ContentControl.Style>  
</ContentControl>