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; }
When CurrentStatus is changed, OnPropertyChanged is called.
I need somehow to trigger this DataTemplateSelector when the property is changed and change ContentPresenter DataTemplate. Any suggestions?
Threre are similar questions: 1 2, but I don't want to use any DataTriggers, because of too much states.
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>
But got an error: Triggers collection members must be of type EventTrigger :(
As you requested an example with datatriggers in the comments, here you are:
A FrameworkElement can only have EventTriggers, therefore you get the error Message Triggers collection members must be of type EventTrigger
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?
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>
I could be wrong, but I believe the DataTemplateSelector
is only used when the ItemContainerGenerator
creates a container for an item added to the collection. Because a new container isn't generated when a property value changes, a new DataTemplate
is never going to be applied via the selector.
As suggested in the comments, I would recommend you look at the VisualStateManager
or data triggers, otherwise you're going to have to recreate the container for every item when one or more properties change value.
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