WPF how to access other variable from same viewmodel?

Question

To display items on Telerik:RadGridView usually I use DataContext="{Binding [someViewModel]}" and ItemSource="{Binding objectList, Mode=TwoWay}".

and for my column I'll access the objectfield. The overall picture will be something like below:

<telerik:RadGridView DataContext="{Binding [someViewModel]}" 
     ItemSource="{Binding objectList, Mode=TwoWay}">

    <telerik:RadGridView.Columns>
            <telerik:GridViewDataColumn>
                <telerik:GridViewDataColumn.CellTemplate>
                    <DataTemplate>
                        <CheckBox IsEnabled="{Binding enabledVar}" 
                            IsChecked="{Binding isChecked, Mode=Twoway}"
                    </DataTemplate>
                </telerik:GridViewDataColumn.CellTemplate>

            </telerik:GridViewDataColumn>  
    </telerik:RadGridView.Columns>

</telerik:RadGridView>

Imagine there will be 10 items in objectList. Each of the item in objectList will have a variable isChecked which to manipulate the checkbox IsChecked property.

I have another variable in the same viewmodel named enabledVar which to control the ten checkbox IsEnabled property. enabledVar is not part of the objectList but I couldn't get the value. May I know how to handle such case?

Updates:

I've found some new direction but not sure if it helps.

<CheckBox IsEnabled="{Binding enabledVar,
     RelativeSource={RelativeSource Mode=FindAncestor, 
     AncestorType=telerik:RadGridView}}"

but then of course, still failed.

Any helps would be very much appreciated.

Answer 1

if using Ancestor you have to bind to DataContext

<CheckBox IsEnabled="{Binding Path=DataContext.enabledVar,
     RelativeSource={RelativeSource Mode=FindAncestor, 
     AncestorType=telerik:RadGridView}}"

Another aproach could be to use element binding set name

<telerik:RadGridView x:Name="myGrid" ...

And then in the celltemplate bind to it

<CheckBox IsEnabled="{Binding Path=DataContext.enabledVar, ElementName=myGrid}"

Hope this helps.

Answer 2

The code suggested in Update will not work because GridViewDataColumn is not part of the Visual tree, and hence can not access DataContext.

You will have to make use of proxy data binding, like suggested here. You can get more examples by searching "wpf proxy databinding".