Question

For some reason I am unable to bind to ViewModel properties within DataTemplates on some controls. The result of the binding itself is unpredictable, sometimes it work, sometimes it doesn’t. For this reason I am thinking of exposing the ViewModel in some other way besides setting it as DataContext.

First thought was to add ViewModel to Resources collection. I am using TabControls for UI, so whenever a view needs to be displayed, it is done through Data templates.

<DataTemplate DataType="{x:Type vm:SomeViewModel}">
    <vw:SomeView />
</DataTemplate>

In this situation the view is instantiated automatically, and its DataContext is set to ViewModel set in template. Is there a way I can make this ViewModel available to View’s Resources (ex with key=viewModel), so that I can use it like this:

<TextBlock Text="{Binding SomeProperty, Source={StaticResource viewModel}}" />

I have tried adding it in code, in the Loaded event for the View:

this.Loaded += (s, e) =>
{
    this.Resources.Add("viewModel", this.DataContext);
};

Above code is executed before the error pops up that says static resource is not found at run-time, so the resource was added to collection.

Any ideas what can I do?

Answer 1

You can define ViewModel as a resource in XAML like that:

<vm:SomeViewModel x:Key="ViewModel"/>

If you want to Bind to DataContext in a DataTemplate you can use the following:

{Binding Path=DataContext, ElementName=uc}

assuming that your window/usercontrol name is x:Name=”uc” , or as @stukselbax wrote:

{Binding Path=DataContext, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=[UserControl|Window]}}