MVVM の場合は、SelectedItem または SelectedIndex のバインドを使用します。そうでない場合は、それを使用することをお勧めします)
目標を達成するには、SelectedIndex をバインドし、行を追加するたびに SelectedIndex を RowsCount-1 に設定します。
ここに例があります。
<Grid >
<DataGrid AutoGenerateColumns="False" CanUserAddRows="False" ItemsSource="{Binding Path=Persons}" Margin="0,65,0,0"
SelectedIndex="{Binding Path=SelectedIndex, Mode=TwoWay}">
<DataGrid.Columns>
<DataGridTextColumn Header="First name" Binding="{Binding Path=FirstName}" Width="*"/>
<DataGridTextColumn Header="Last name" Binding="{Binding Path=LastName}" Width="*"/>
</DataGrid.Columns>
</DataGrid>
<Button Content="Add new row" Height="23" HorizontalAlignment="Left" Margin="317,12,0,0" Command="{Binding Path=AddCommand}" VerticalAlignment="Top" Width="112" />
</Grid>
とビューモデル
public class MainViewModel : INotifyPropertyChanged
{
private int _selectedPerson;
public MainViewModel()
{
AddCommand = new RelayCommand(AddAndSelectePerson);
Persons = new DataTable();
Persons.Columns.Add("FirstName");
Persons.Columns.Add("LastName");
Persons.Rows.Add("Alexandr", "Puskin");
Persons.Rows.Add("Lev", "Tolstoy");
}
public ICommand AddCommand { get; private set; }
public int SelectedIndex
{
get { return _selectedPerson; }
set
{
_selectedPerson = value;
OnPropertyChanged("SelectedIndex");
}
}
public DataTable Persons { get; private set; }
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
#endregion
private void AddAndSelectePerson()
{
Persons.Rows.Add();
SelectedIndex = Persons.Rows.Count - 1;
}
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public class RelayCommand : ICommand
{
private readonly Action _actionToExecute;
public RelayCommand(Action actionToExecute)
{
_actionToExecute = actionToExecute;
}
#region ICommand Members
public void Execute(object parameter)
{
_actionToExecute();
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
#endregion
}
public class Person
{
public Person()
{
}
public Person(string firstName, string lastName)
{
FirstName = firstName;
LastName = lastName;
}
public string FirstName { get; set; }
public string LastName { get; set; }
}
試す例