如何触发DataTemplateSelector属性发生变化时？ [英] How to trigger DataTemplateSelector when property changes?

问题描述

我有内容presenter与DataTemplateSelector：

I have ContentPresenter with DataTemplateSelector:

    ...

    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var model = item as ItemControlViewModel;

        if (model.CurrentStatus == PrerequisitesStatus.Required)
        {
            return RequiredTemplate;
        }

        if (model.CurrentStatus == PrerequisitesStatus.Completed)
        {
            return FinishedTemplate;
        }

        ...

        return InProgressTemplate;
    }

当CurrentStatus改变时，OnPropertyChanged称为

When CurrentStatus is changed, OnPropertyChanged is called.

我需要以某种方式当属性更改为触发此DataTemplateSelector和更改内容presenter的DataTemplate。有什么建议？

I need somehow to trigger this DataTemplateSelector when the property is changed and change ContentPresenter DataTemplate. Any suggestions?

Threre有类似的问题：
<一href=\"http://stackoverflow.com/questions/3543515/wpf-reapply-datatemplateselector-when-a-certain-value-changes\">1
<一href=\"http://stackoverflow.com/questions/2376173/wpf-activate-trigger-when-a-mvvm-bound-property-changes\">2,但我不希望使用任何DataTriggers，因为太多的状态。

Threre are similar questions: 1 2, but I don't want to use any DataTriggers, because of too much states.

试图与DataTriggers玩

Tried to play with DataTriggers

    <ContentPresenter
        Grid.Column="1"
        Height="16"
        Width="16"
        Margin="3">
        <ContentPresenter.Triggers>
            <DataTrigger Binding="{Binding Path=CurrentStatus}" Value="0">
                <Setter Property="ContentPresenter.ContentTemplate" Value="{StaticResource ResourceKey=_requiredStatusTemplate}" />
            </DataTrigger>
        </ContentPresenter.Triggers>
    </ContentPresenter>

但得到了一个错误：
Triggers集合成员必须是类型的EventTrigger的：（

But got an error: Triggers collection members must be of type EventTrigger :(

推荐答案

根据您的要求与意见datatriggers一个例子，在这里你是：

As you requested an example with datatriggers in the comments, here you are:

一个FrameworkElement的只能有EventTriggers，因此，你得到错误信息的 Triggers集合成员必须是类型的EventTrigger 的

A FrameworkElement can only have EventTriggers, therefore you get the error Message Triggers collection members must be of type EventTrigger

和也不会直接使用内容presenter，是指一个的ControlTemplate内使用。如果你想拥有动态内容更好的使用ContentControl中。
见<一href=\"http://stackoverflow.com/questions/1287995/whats-the-difference-between-contentcontrol-and-content$p$psenter\">What's ContentControl中和内容presenter区别？

And also don't use a ContentPresenter directly, it is meant to be used inside a ControlTemplate. Better use a ContentControl when you want to have dynamic content. See What's the difference between ContentControl and ContentPresenter?

和终于在这里有一个建议您DataTrigger问题。我已经把它的风格里面重用....

And finally here's a suggestion to your DataTrigger issue. I have put it inside a style for reusability ....

XAML：

<Window x:Class="WpfApplication88.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
  <Window.Resources>

    <DataTemplate x:Key="requiredTemplate">
      <TextBlock Text="requiredTemplate"></TextBlock>
      <!--your stuff here-->
    </DataTemplate>

    <DataTemplate x:Key="completedTemplate">
      <TextBlock Text="CompletedTemplate"></TextBlock>
      <!--your stuff here-->
    </DataTemplate>

    <Style x:Key="selectableContentStyle" TargetType="{x:Type ContentControl}">
      <Style.Triggers>
        <DataTrigger Binding="{Binding Path=CurrentStatus}" Value="Required">
          <Setter Property="ContentTemplate" Value="{StaticResource requiredTemplate}" />
        </DataTrigger>
        <DataTrigger Binding="{Binding Path=CurrentStatus}" Value="Completed">
          <Setter Property="ContentTemplate" Value="{StaticResource completedTemplate}" />
        </DataTrigger>
        <!--  your other Status' here -->
      </Style.Triggers>
    </Style>

  </Window.Resources>

  <Grid>
    <ContentControl Width="100" Height="100" Style="{StaticResource selectableContentStyle}"/>
  </Grid>

</Window>

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