How to collapse the details view datagrid inside the Groups in DataGrid

About the sample

By default, DetailsViewDataGrid expanded state is maintain when group of WinForms DataGrid (SfDataGrid) is collapsed. If we need to collapse the DetailsViewDataGrid when group of DataGrid is collapsed, this can be achieved by disabling the IsExpanded of DetailsViewDataGrid in SfDataGrid.GroupExpanding event.

this.sfDataGrid1.GroupExpanding += SfDataGrid1_GroupExpanding;

private void SfDataGrid1_GroupExpanding(object sender, Syncfusion.WinForms.DataGrid.Events.GroupChangingEventArgs e)
{
    CollapseAllNestedGrids(e.Group);
}

void CollapseAllNestedGrids(Group group)
{
    if (group != null && group.Records != null)
    {
        foreach (var item in group.Records)
        {
            if (item.IsGroups == false)
                item.IsExpanded = false;
        }
    }
    if (group.Groups != null)
    {
        foreach (var item in group.Groups)
            CollapseAllNestedGrids(item);
    }
}

Requirements to run the demo

Visual Studio 2015 and above versions