DataContext not binding in Style.Trigger - wpf

Question

So I have some code similar to the following: (Forgive any typos-- I tried to simplify in the SO editor for the post)
<my:CustomContentControl>
<my:CustomContentControl.Style>
<Style TargetType="{x:Type my:CustomContentControl}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=CurrentView}" Value="MyCustomView">
<Setter Property="Content">
<Setter.Value>
<my:CustomView DataContext="{Binding DataContextForMyCustomView"/>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</m:CustomContentControl.Style>
</my:CustomContentControl>
The problem is that whenever the DataTrigger occurs, the setter does set the Content property to my:CustomView, but it does not bind DataContext. If I move the same code outside of the trigger the DataContext binding works just fine.
Any ideas? If this is a limitation of some sorts, is there any work around?
Update:
I received the following error in the output window:
System.Windows.Data Error: 3 : Cannot find element that provides DataContext. BindingExpression:Path=DataContextForMyCustomView; DataItem=null; target element is 'CustomView' (Name='customView'); target property is 'DataContext' (type 'Object')

Answer 1

The error you posted makes it sound like your custom control is in an object that doesn't have a DataContext, such as a DataGridColumn.Header.
To get around that, you can create a Freezeable object in your .Resources containing the binding you're looking for, then bind your my:CustomView.DataContext to that object
<my:CustomContentControl.Resources>
<local:BindingProxy x:Key="proxy"
Data="{Binding DataContextForMyCustomView, ElementName=MyControl}" />
</my:CustomContentControl.Resources>
...
<my:CustomView DataContext="{Binding Source={StaticResource proxy}}"/>
Here's the code for a sample Freezable object copied from here:
public class BindingProxy : Freezable
{
#region Overrides of Freezable
protected override Freezable CreateInstanceCore()
{
return new BindingProxy();
}
#endregion
public object Data
{
get { return (object)GetValue(DataProperty); }
set { SetValue(DataProperty, value); }
}
// Using a DependencyProperty as the backing store for Data.
// This enables animation, styling, binding, etc...
public static readonly DependencyProperty DataProperty =
DependencyProperty.Register("Data", typeof(object),
typeof(BindingProxy), new UIPropertyMetadata(null));
}
Also, you really should use ContentTemplate instead of Content to avoid an exception if more than one object applies that style :)

Answer 2

I solved a similar problem by putting the UserControl into the resources and then changing the Content with that.
e.g. from my own code (different names, same concept)
<ContentControl Grid.Column="1"
Margin="7,0,7,0">
<ContentControl.Resources>
<mapping:Slide11x4MappingView x:Key="Slide11X4MappingView" DataContext="{Binding MappingViewModel}"/>
<mapping:MicrotubeMappingView x:Key="MicrotubeMappingView" DataContext="{Binding MappingViewModel}"/>
</ContentControl.Resources>
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Style.Triggers>
<DataTrigger Binding="{Binding Acquirer.Sorter.TrayType}" Value="{x:Static mapping:TrayType.SLIDES11X4}">
<Setter Property="Content" Value="{StaticResource Slide11X4MappingView}"/>
</DataTrigger>
<DataTrigger Binding="{Binding Acquirer.Sorter.TrayType}" Value="{x:Static mapping:TrayType.VIALS}">
<Setter Property="Content" Value="{StaticResource MicrotubeMappingView}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>