ContentTemplateSelector仅被调用一次,始终显示相同的datatemplate

Question

我已经制作了一个示例演示VS 2010 RC示例项目,因为在我的生产项目中我使用MVVM时遇到了同样的错误.

在我的示例演示项目中,我只使用Code-behind而没有第三方依赖,因此您可以在此处下载演示项目并自行运行:http://www.sendspace.com/file/mwx7wv

现在问题:当我点击女孩/男孩按钮时,它应该切换datatemplate,不是吗？

我错了什么？

好的,我在这里也提供了一个代码片段:

代码隐藏在MainWindow.cs:

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(通过您提供的链接在Josh的帖子中找到):

<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工作,但这使用一种风格:

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

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

  </Style.Triggers>