Question

I’m trying to find out where the items in a HeaderedContentControl come from in a project that’s not mine. Here’s the code:

        <HeaderedContentControl 
            Content="{Binding Path=Workspaces}"
            ContentTemplate="{StaticResource WorkspacesTemplate}"
            Header="Workspaces"
            Style="{StaticResource MainHCCStyle}" 
            DataContext="{Binding}" // <--- this 
       />

<DataTemplate x:Key="WorkspacesTemplate">
<TabControl 
  IsSynchronizedWithCurrentItem="True" 
  ItemsSource="{Binding}" 
  ItemTemplate="{StaticResource ClosableTabItemTemplate}"
  Margin="4"
  />

so let’s examine it:

1. ContentTemplate attribute describes how the items are desplayed.
2. WorkspacesTemplate sets ItemsSource’s attribute to {Binding} meaning it’s bound to its DataContext property (DataContext of HeaderedContentControl)
3. So I look at HeaderedContentControl’s dataContext, but it is described as “{Binding}” as well…

What does that mean?

Answer 1

Without seeing more of your code it is hard to be certain, but DataContext="{Binding}" is quite often unnecessary, as any object in the current binding context will automatically have its DataContext property set to the equivalent of {Binding}.

Remember:

• Property="{Binding}" means “set this.Property to the evaluated value of this.DataContext“
• Property="{Binding Path=SubProperty}" means “set this.Property to the evaluated value of this.DataContext.SubProperty“
• etc

This means that DataContext="{Binding}" means “set this.DataContext to the evaluated value of this.DataContext“, which (in most cases) is redundant!