Expand and Collapse Groups in .NET MAUI DataGrid
The Telerik UI for .NET MAUI DataGrid supports group expand and collapse operations either through the UI by tapping on the group headers, or programmatically. By default, all the groups are expanded.
This section provides an overview of the methods and commands used to control the expand/collapse state of the DataGrid groups.
Get the Grouped DataGrid Items
To manipulate the collapsible DataGrid groups, first you will need to call its GetDataView method. In short, the GetDataView method provides a view of the ItemsSource after all the sorting, grouping, and filtering operations are applied. The return type is IDataViewCollection which exposes the expand and collapse methods described in the following sections.
var dataView = this.dataGrid.GetDataView();
Expand and Collapse All Groups
To expand all groups, use the ExpandAll method and, respectively, the CollapseAll method to collapse all groups.
//expand all
var dataView = this.dataGrid.GetDataView();
dataView.ExpandAll();
//collapse all
var dataView = this.dataGrid.GetDataView();
dataView.CollapseAll();
Expand and Collapse Specific Groups
You can retrieve the first-level groups through the GetGroups method of the IDataViewCollection object and use ExpandGroup/CollapseGroup to make a certain group to expand or collapse respectively. You can check whether a group is expanded trough the GetIsExpanded method.
The following example demonstrates how these methods are used:
var dataView = this.dataGrid.GetDataView();
var rootGroups = dataView.GetGroups();
var isFirstExpanded = dataView.GetIsExpanded(rootGroups.First());
//expand a certain group
dataView.ExpandGroup(rootGroups.First());
//collapse a certain group
dataView.CollapseGroup(rootGroups.First());
Additionally, IDataViewCollection provides the ExpandItem/CollapseItem methods that take a data item as a parameter and expand/collapse the immediate group containing this item.
var lastItem = (dataGrid.ItemsSource as IEnumerable<City>).Last();
var dataView = this.dataGrid.GetDataView();
dataView.CollapseItem(lastItem);