Question

I have an application that needs to display a set of rows that is filtered by some external criteria. For reasons I won’t explain here, I don’t really want to remove the rows from the DataTable the DataGrid is bound to. To filter the list, I am collapsing the rows that I don’t want to show. This works great, until the user sorts the DataGrid. After the sort has been completed, the collapsed rows are suddenly visible again. I looked for an Sorted event so that I could just re-collapse the rows I needed, but there is only a Sorting event. I tried to use the IsVisibleChanged on each DataGridRow, but this doesn’t seem to be firing. How do I resolve this issue?

Here is a simple demo of the problem:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        DataTable table = new DataTable();
        table.Columns.Add("Column 1");

        DataRow row = table.NewRow();
        row[0] = "1";
        table.Rows.Add(row);

        row = table.NewRow();
        row[0] = "2";
        table.Rows.Add(row);

        row = table.NewRow();
        row[0] = "3";
        table.Rows.Add(row);

        _grid.ItemsSource = table.AsDataView();
        _grid.DataContext = table;
        _grid.Loaded += _grid_Loaded;
    }

    void _grid_Loaded(object sender, RoutedEventArgs e)
    {
        var dataGridRow = GetRow(_grid, 1);
        dataGridRow.Visibility = Visibility.Collapsed;

        dataGridRow = GetRow(_grid, 0);
        dataGridRow.Visibility = Visibility.Collapsed;
    }

    public DataGridRow GetRow(DataGrid grid, int index)
    {
        var row = (DataGridRow)grid.ItemContainerGenerator.ContainerFromIndex(index);
        if (row == null)
        {
            // May be virtualized, bring into view and try again.
            grid.UpdateLayout();
            if (grid.Items.Count > index)
            {
                grid.ScrollIntoView(grid.Items[index]);
                row = (DataGridRow)grid.ItemContainerGenerator.ContainerFromIndex(index);
            }
        }
        return row;
    }
}

Here is the XAML:

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <DataGrid HorizontalAlignment="Left" Margin="54,43,0,0" VerticalAlignment="Top" Height="216" Width="382" Name="_grid"/>

</Grid>

After running the program, you will see a DataGrid with only the number 3. Click “Column 1” to sort by the column, notice you now have the number 1, 2, and 3.

Any help solving this problem will be greatly appreciated.

Answer 1

I think you should be concentrating on filtering the DataTable rather than the DataGridView. Have you tried using DataView’s in the past? You can use these to filter your DataTable and as you have a bound DataGridView the View will reflect through in the GridView?

By filtering the DataTable, you are not removing any rows, your simply altering the way it looks temporarily.

Here’s a link that may help :-

http://msdn.microsoft.com/en-us/library/system.data.dataview.rowfilter.aspx

I hope this helps.