Question

It’s a good thing I don’t mind feeling stupid.

I’m trying to bind to an ObservableCollection on my view model. The data hierarchy looks like: Parent -contains list of- Child objects. Nothing complicated.

At the outermost grid of my Xaml tree I establish a link to the view model with:

<Grid DataContext="{StaticResource src}">

Yes, src does reference the view model and the two dozen bindings before the problem textbox work fine. There is not another DataContext in my Xaml tree. Now I come to a simple textbox. I want to bind Textbox text to a child.property.

This works:

  <TextBlock 
     DataContext="{Binding Parent}"
     Text="{Binding Path=Child.Property}"
     Style="{StaticResource headerMajor}"
  />

This doesn’t work:

  <TextBlock 
     Text="{Binding Source=Parent,Path=Child.Property}"
     Style="{StaticResource headerMajor}"
  />

I thought they were two ways of saying the same thing. Ordinarily I wonder for a moment and then keep on coding. However, some advice I’ve read mentioned that DataContext attributes buried in Xaml controls can lead to hard to find bugs.

Please explain why one works and the other does not. This will help my grasp on the whole binding topic.

Jim

Answer 1

Source is a property which holds an object used as source for the binding, it does not resolve to a property. Hence your binding is looking for the property path Child.Property on the string "Parent", see the problem?