wpf - how can I create a dependency between expander inside datagrid and one of datagridrow properties

Question

This is a general question. And may not be specific to datagrids. How can i related 2 properties or 2 different UI Elements/controls

Like Each datagridRow has an Expander and i want the IsExpanded property to be dependent on datagridrow selected event .

Thank you

Answer 1

A relative source binding can be used to bind two properties without referring to the source element by name. This is especially useful is styles.

Here's an example of a ListBox with items that expand when selected.

<ListBox>
    <ListBox.ItemTemplate>
        <DataTemplate>
            <Expander
                Header="{Binding}"
                IsExpanded="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ListBoxItem}, Path=IsSelected}">
                <TextBlock
                    Text="{Binding}" />
            </Expander>
        </DataTemplate>
    </ListBox.ItemTemplate>

    <sys:String>a</sys:String>
    <sys:String>b</sys:String>
    <sys:String>c</sys:String>
    <sys:String>d</sys:String>

</ListBox>

When I need a fancy binding, I regularly use a cheat sheet posted by Nir on his blog and referenced in the StackOverflow question Is there a WPF Cheat Sheet outhere?.

Here's the cheat sheet direct link.

If you ever read this, thanks Nir.