绑定到模板中的嵌套属性

Question

I want to create a button with loading indicator for async methods, like this:

I create an AsyncCommand implementing ICommand and INotifyPropertyChanged (more details in MSDN Magazine April, 2014).

My AsyncCommand has Execution property and it has IsNotCompleated property. I want to set Visibility property of loader indincator using IsNotCompleted property.

I create UserControl inherits the Button and set style for this. I try to bind visibility to Button's Command dependency property.

There the part of ControlTemplate with "Loading indicator" (I use content, not Visibility, just for example)

 <Label HorizontalAlignment="Center"
        VerticalAlignment="Center"
        Grid.Column="1"
        Content="{Binding Command.Execution.IsNotCompleted}"/>

And nothing happens. If i use TemplateBinding instead of Binding I'll get compile errors:

• Nested types not supported: Command.Execution
• Unable to find type Command.Execution

What is the correct way to do this?

Answer 1

The solution is using RelativeSource.TemplatedParent

<Label HorizontalAlignment="Center"
    VerticalAlignment="Center"
    Grid.Column="1"
    Content="{Binding Command.Execution.IsNotCompleted, RelativeSource={RelativeSource TemplatedParent}}"/>