Group expanding and collapsing events

[Brian Lam]

Hi,

I'm trying to defer loading the detail rows inside RadGridView's groups until the group header is expanded; when the group header is collapsed, I just have a dummy row of data representing the group. To do this, I need GroupExpanded/Collapsed events. Are there any such events provided by RadGridView, or are there any plans to add them in the future?

- Brian

[Rossen Hristov]

Hello Brian Lam,

You can try with GridViewRow.IsExpandedChanged - occurs when GridViewRow changes its IsExpanded state. The type of the passed event arguments is RoutedEventArgs.

I hope this helps.

Regards,
Ross
the Telerik team

[Brian Lam]

I'm trying to track the expansion of groups, not hierarchical rows. GridViewRow.IsExpandedChanged is an event on the data rows; I need a way to track changes to GridViewGroupRow.IsExpanded, which doesn't inherit from GridViewRow.

Also, is there a way to get references to the GridViewGroupRows as they're added to/removed from the grid? It looks like they don't exist by the time the RadGridView.Grouped event is raised. For example, if I have an event handler like:

private void TheGrid_Grouped(object sender, GridViewGroupedEventArgs e)
{
 if (TheGrid.Items.Groups != null)
 {
  var groupContainers = TheGrid.Items.Groups.Select(group => TheGrid.ItemContainerGenerator.ContainerFromItem(group)).Cast<GridViewGroupRow>().ToList();
 }
}

Then TheGrid.Items.Groups is always null when I add the first grouping.

[Rossen Hristov]

Hi Brian Lam,

I am sorry for the misunderstanding.

We do not have such events for the groups and this is by design.

You are trying to achieve lazy-loading of groups which will break a lot of functionality such as aggregates, calculations for virtualization, etc, virtually everything. That is why we have not provided it out of the box.

Sincerely yours,
Ross
the Telerik team