Selecting a row in a grid control from code

Question

I am writing an application that uses two grid controls. If the user selects a row in the left grid control, the corresponding row in the right grid control must be selected from code. For both grids I am using a grid control derived class that allows the user to select multiple rows at the same time.The code to select a row from code works, the problem I am facing is that (apparently) other rows are not properly unselected. When selecting multiple rows afterwards in the right grid control (by clicking a row and then another one using shift+click) a lot more rows are selected than expected.

public class CustomDataGrid : DataGrid
{
    public CustomDataGrid()
    {
        SelectionChanged += CustomDataGrid_SelectionChanged;
    }

    void CustomDataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        SelectedItemsList = SelectedItems;
    }

    #region SelectedItemsList

    public IList SelectedItemsList
    {
        get { return (IList)GetValue(SelectedItemsListProperty); }
        set { SetValue(SelectedItemsListProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemsListProperty =
            DependencyProperty.Register("SelectedItemsList", typeof(IList), typeof(CustomDataGrid), new PropertyMetadata(null));

    #endregion
}

In the xaml file it is used like this:

<vm:CustomDataGrid ItemsSource="{Binding LeftGridItems}" SelectedItemsList="
{Binding SelectedLeftGridItems, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
AutoGenerateColumns="False" SelectionMode="Extended" IsReadOnly="True" 
CanUserAddRows="False" Margin="7,0,7,7" Grid.Row="3" Grid.Column="0">
    <DataGrid.Columns>
        ...

The code for the selection in the left grid:

public IList SelectedLeftGridItems
{
    get { return _selectedLeftGridItems; }
    set
    {
        _selectedLeftGridItems = value;

        // Select the copy on the right side, if available
        if (_selectedLeftGridItems != null && _selectedLeftGridItems.Count > 0)
        {
            Element selected = ((Element)SelectedLeftGridItems[0]);
            if (!string.IsNullOrEmpty(selected.CopyOf))
            {
                SelectedRightGridItems.Clear();
                SelectedRightGridItems.Add(RightGridItems.FirstOrDefault(e => Path.GetFileName(e.Path) == Path.GetFileName(selected.CopyOf)));
                OnPropertyChanged("SelectedRightGridItems");
            }
        }

        OnPropertyChanged("SelectedLeftGridItems");
    }
}

How can I ensure that the selected items in the right grid are properly administered?

Answer 1

Doing "selecting multiple rows" in a grid could be a PITA based on shift-click, ctrl-click, single-click that could cancel everything else already marked.

One thing I have done is to add a checkbox control as the first column in a grid that is bound to a property on the row source control to a property such as

public bool IsChosen {get; set;}

Then, in your code, your underlying row source for the grid display could do...

foreach( var xRow in DataGridRowSource.Where( s => s.IsChosen ))
{
   // find in other grid and similarly mark
}