I have an xamdatagrid within which there is column of type combobox, now I want to get the selectedrowindex of xamdatagrid if I am makin any change to selection of combobox.

I have used below style for adding combobox as fieldtype within xamdatagrid but I am not getting the value of commandparameter within the viewmodel, I am always getting value of Object O within ContinueSave(object o) as null

<Style x:Key="combo" TargetType="{x:Type idp:CellValuePresenter}">
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<ComboBox ItemsSource="{Binding Path=DataContext.DataItem.Options,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type idp:CellValuePresenter}}}"
DisplayMemberPath="Label"
SelectedItem="{Binding Path=DataContext.DataItem.Value,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type idp:CellValuePresenter}}}">

<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<i:InvokeCommandAction
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.SelectionChangeCommand, Mode=OneWay}"
CommandParameter="{Binding Path=DataContext.DataItem.CalcSequence}"/>

</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>

Here is the code in viewmodel:

private DelegateCommand<object> selectionChangeCommand;

/// <summary>
/// Handle grid header column mapping command
/// </summary>
public DelegateCommand<object> SelectionChangeCommand
{
get
{
if (selectionChangeCommand == null)
selectionChangeCommand = new DelegateCommand<object>(param => this.ContinueSave(param), param => true);
return selectionChangeCommand;
}
}
private void ContinueSave(object o)
{
// Do something
}