Question

I have a workable solution but I’m pretty convinced there’s a better way of writing this.

I have a User Control with a Data Grid inside. The Data Grid’s ItemsSource is set to {Binding Path=MyView} where MyView is an ICollectionView property of the View Model. The User Control’s data context is set to the View Model.

In the data grid, I have a check box header. I want to bind the IsChecked state of the checkbox to a property in the View Model.

This is what I have so far and it seems to work, but I’m concerned this binding is unnecessarily complex. The UI is pretty basic so I would expect the binding to be more straightforward to write than it was.

Is there a better way to express such a binding?

<DataGridTemplateColumn.HeaderTemplate>
    <DataTemplate>
         <CheckBox IsChecked="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Views:MyUserControlClass}}, Path=DataContext.AllRowsSelected}" />
    </DataTemplate>
</DataGridTemplateColumn.HeaderTemplate>

Answer 1

In such situations I use

ElementName=userControl

instead of

RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Views:MyUserControlClass}}

Also you can use

{Binding Parent.DataContext.AllRowsSelected, ElementName=LayoutRoot}

In this case I assume that LayoutRoot is the name of the element who’s parent is the user control. Parent is its property. So binding is set to parent’s DataContext property.

I prefer the last variant, because providing name for user control limits its usage.

EDIT

About LayoutRoot. This name is often provided for the top element in a Window or a UserControl, or just some layout:

<Window ...>
    <Grid Name="LayoutRoot">
        ...
    </Grid>
</Window>

There’s nothing special about this name. Just often used. Same situation as with namespace aliases in xaml: sys (points to mscorlib), local (points to your application namespace), etc.