Data binding when "RelativeSource" is used in MVVM

[mwdpb]

I have a custom DataGrid with one column being ComboBox whose selected value is row-specific but its ItemSource should be globally bond. The properties structure is:

VM level:

PPTPlots {get; set}

Inside PPTPlots:

Items {get; set}
VisualTitles {get; set}

Inside VisualTitles:

Items {get; set}

and the DataGrid is written as below:

<DataGrid ItemsSource="{Binding PPTPlots.Items}">
    <DataGrid.Columns>
        <DataGridTemplateColumn>
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <ComboBox ItemsSource="{Binding PPTPlots.VisualTitles.Items}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

The above code does not work as WPF is trying to bind ItemSource to xxx.VisualTitle (xxx is the type of PPTPlots.Items). It basically uses the data row's context, instead of viewmodel's context.

So to remedy the problem, I changed the binding syntax to:

<ComboBox ItemsSource="{Binding PPTPlots.VisualTitles.Items, RelativeSource={RelativeSource AncestorType=UserControl}}"/>

Now VS complained property not found in the view. Since the property is defined in the viewmodel, it makes sense that it can't be found in the view. So my question is in Stylet how can we make it looking for property in the view model (not in the view) when the RelativeSource clause is used?

[canton7]

The normal wpf way is {Binding DataContext.PPTPlots....}

[mwdpb]

What syntax should I use? I tried below, and obviously it doesn't work. For command binding, Stylet has s.View.ActionTarget, I was thinking if there's similar syntax to explicitly specify the datacontext.

[canton7]

This is just a normal WPF binding, nothing to do with Stylet.

<ComboBox ItemsSource="{Binding DataContext.PPTPlots.VisualTitles.Items, RelativeSource={RelativeSource AncestorType=UserControl}}"/>

[canton7]

My normal trick here is to name the View:

<UserControl x:Name="root"...

Then use in the binding:

<ComboBox ItemsSource="{Binding DataContext.SomeVmProperty, ElementName=root}" 

[mwdpb]

Gotcha and it works great! Thank you so much and a trick learned! :)

[canton7]

Great!