Wpf how to do a contextmenu only on a datagrid row

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C#

XAML

WPF

MVVM

DataGrid

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I've been learning C# for years, and finally decided to learn and use WPF and MVVM, and no code-behind. This is my first app, and for the most part, it's going rather well. I haven't been able to find an answer to the following problem.

I have a simple application where I have a WPF executable front end and a DLL class library back end. The front end has a DataGrid that is bound to a DataTable in a ViewModel class; which I populate from a query to an SQL 2000 database when the user requests it. I'd like to be able to let the user right-click on a row in a DataGrid and display a ContextMenu that when clicked, opens a browser and displays information related to the ticket for the row that was clicked. That ContextMenu item is a command in the ViewModel class that starts a process that opens a URL and uses text from one of the columns for the DataRowView for the specific item that was right-clicked. Aside from not being sure if I should operate off the SelectedItem or SelectedIndex to reference directly with the DataTable (perhaps there could be a time when the indexes are different?)--for the most part, that's working with roughly the following code:

Some of the XAML:

<DataGrid
    x:Name="TicketsDataGrid"
    ItemsSource="{Binding TicketsViewModel.TicketsDataTable}"
    AutoGenerateColumns="True"
    CanUserAddRows="False"
    CanUserSortColumns="True"
    CanUserResizeRows="False"
    IsReadOnly="True"
    SelectionMode="Single"
    SelectionUnit="FullRow">
    <DataGrid.ContextMenu>
        <ContextMenu>
            <MenuItem
                Header="View Ticket in browser"
                Command="{Binding Path=TicketsViewModel.ViewTicketInBrowser_Command}"
                CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=PlacementTarget.SelectedItem}"/>
        </ContextMenu>
    </DataGrid.ContextMenu>
</DataGrid>

Part of TicketsViewModel:

private RelayCommand viewTicketInBrowser_Command;

public ICommand ViewTicketInBrowser_Command
{
    get
    {
        return this.viewTicketInBrowser_Command ?? (this.viewTicketInBrowser_Command = new RelayCommand(this.ViewTicketInBrowser_Command_Execute, param => ViewTicketInBrowser_Command_CanExecute()));
    }
}

public bool ViewTicketInBrowser_Command_CanExecute()
{
    return true;
}

public void ViewTicketInBrowser_Command_Execute(object ticketObject)
{
    if (ticketObject != null)
    {
        if (ticketObject.GetType() == typeof(System.Data.DataRowView) && ((System.Data.DataRowView)ticketObject).Row.Table.Columns.Contains("TicketNumber"))
        {
            System.Diagnostics.Process.Start("http://mysite/ticket_detail.asp?ticketnum=" + ((System.Data.DataRowView)ticketObject).Row.Field<string>("TicketNumber"));
        }
    }
}

The above works, but will allow right-click and the ContextMenu anywhere in the DataGrid. I only want it to be available if you right-click on a row in the DataGrid. Ideally I'd like to get the row that was clicked, however only know how to get the SelectedItem or SelectedIndex. So I figured if I limited to just allowing the ContextMenu on the row, that could be the best option. I can see where a ContextMenu would be good for many things on the DataGrid itself; but for just the row, it seemed odd to let it happen just anywhere on the DataGrid.

What I have tried:

I tried several ideas from searches, such as defining the ContextMenu in the DataGrid.Resources area, then setting a DataGrid.RowStyle, but I don't seem to have that right. It seems to limit the ContextMenu to just the row, but I cant seem to wire it correctly to my command.

Alternate XAML I tried:

<DataGrid.Resources>
    <ContextMenu
        x:Key="RowMenu"
        DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
        <MenuItem
            Header="View Ticket in browser"
            Command="{Binding Path=TicketsViewModel.ViewTicketInBrowser_Command}"
            CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}, Path=PlacementTarget.SelectedItem}" />
    </ContextMenu>
</DataGrid.Resources>
<DataGrid.RowStyle>
    <Style TargetType="DataGridRow">
        <Setter Property="ContextMenu" Value="{StaticResource RowMenu}" />
    </Style>
</DataGrid.RowStyle>

Have tried several variants and tweaks, but seem to get close to the same two errors in Output:

Error 1:
System.Windows.Data Error: 40 : BindingExpression path error: 'TicketsViewModel' property not found on 'object' ''DataRowView' (HashCode=7742767)'. BindingExpression:Path=TicketsViewModel.ViewTicketInBrowser_Command; DataItem='DataRowView' (HashCode=7742767); target element is 'MenuItem' (Name=''); target property is 'Command' (type 'ICommand')

Error 2:
System.Windows.Data Error: 40 : BindingExpression path error: 'PlacementTarget' property not found on 'object' ''DataGrid' (Name='TicketsDataGrid')'. BindingExpression:Path=PlacementTarget.SelectedItem; DataItem='DataGrid' (Name='TicketsDataGrid'); target element is 'MenuItem' (Name=''); target property is 'CommandParameter' (type 'Object')

I think this is related to the main issue where the Ancestor bindings don't work, as the context menu is not a child of the element it is on; being the DataGrid. The Stack Overflow article "How to set a binding in WPF Toolkit Datagrid's ContextMenu CommandParameter" led me to think that.

Perhaps I've had too much coffee, or have been staring at the screen too long; but need some assistance figuring this out.