Question

How to tell if the entire row in DataGrid selected,

or only a single column

(by Binding or Command, I want to keep the principle of MVVM).

Answer 1

Finally, I found a solution by myself.

(Very Strange that I found nothing about it in a good search.)

Here’s what I did:

I put to two events of the DataGrid bind to Commands sitting in ViewModel.

       <i:EventTrigger EventName="BeginningEdit">
            <i:InvokeCommandAction CommandParameter="{Binding CurrentCell.Column.DisplayIndex, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Command="{Binding DataContext.ColBeginEdit, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
        </i:EventTrigger>
        <i:EventTrigger EventName="CellEditEnding">
            <i:InvokeCommandAction CommandParameter="{Binding CurrentCell.Column.Header, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Command="{Binding DataContext.ColEndEdit, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
        </i:EventTrigger>

In the view model i invok two functions to the commands:

    public void CoulmnBeginEdit(object obj)
    {
        int i;
        if (Int32.TryParse(obj.ToString(), out i))
        {
            if (i > 0)
               this.CurrentCellEdit = i;
        }

    }

    public void CoulmnEndEdit(object obj)
    {
        this.CurrentCellEdit = 0;
    }

If CurrentCellEdit is greater than 0 sign that line editing, otherwise not.

The row number I have on SelectedIndex, and according to the CurrentCellEdit I also know which column editing in the row.

I was hoping to find a simpler way, but this is the only solution that came to mind, to keep the principle of MVVM, and I’m still trying ..