Basic Hierarchies

Telerik Silverlight DataGrid BasicHierarchies 1

RadGridView allows you to display hierarchical data in the form of nested grid views. To do so you have to define a table definition for each subset of data you want to display. Such a definition can be done by creating a GridViewTableDefinition object and adding it to the ChildTableDefinitions collection of the RadGridView.

Defining the GridViewTableDefinition

Specific for the GridViewTableDefinition is that it needs to have its Relation property to the name of the property containing the subset of data. In this way you define the data source for the nested tables. You set the property to an object of type PropertyRelation.

The ParentPropertyName of the PropertyRelation object represents the name of the property that will be used as a source for the nested table.

Example 1: Defining the GridViewTableDefinition

<telerik:GridViewTableDefinition> 
    <telerik:GridViewTableDefinition.Relation> 
        <telerik:PropertyRelation ParentPropertyName="Orders" /> 
    </telerik:GridViewTableDefinition.Relation> 
</telerik:GridViewTableDefinition> 

Example 2: Defining the GridViewTableDefinition programmatically

GridViewTableDefinition td = new GridViewTableDefinition(); 
td.Relation = new PropertyRelation("Orders"); 
Dim td As New GridViewTableDefinition() 
td.Relation = New Telerik.Windows.Data.PropertyRelation("Orders") 

Now you can add the definition to the ChildTableDefinitions collection.

Example 3: Adding the GridViewTableDefinition to the ChildTableDefinitions

<telerik:RadGridView x:Name="radGridView" 
                 AutoGenerateColumns="False"> 
    <telerik:RadGridView.ChildTableDefinitions> 
        <telerik:GridViewTableDefinition> 
            <telerik:GridViewTableDefinition.Relation> 
                <telerik:PropertyRelation ParentPropertyName="Orders" /> 
            </telerik:GridViewTableDefinition.Relation> 
        </telerik:GridViewTableDefinition> 
    </telerik:RadGridView.ChildTableDefinitions> 
</telerik:RadGridView> 

Example 4: Adding the GridViewTableDefinition to the ChildTableDefinitions programmatically

this.radGridView.ChildTableDefinitions.Add(td); 
Me.radGridView.ChildTableDefinitions.Add(d) 

The GridViewTableDefinition object also exposes a ChildTableDefinitions property, which means that you can nest grids on more than one level.

Check If a Hierarchy Item Is Expanded

The IsExpanded method can also be used to check whether a group is expanded. More information can be found in the Programmatic Grouping topic.

In case when checking whether a given hierarchical item is expanded the IsExpanded method of RadGridView comes in handy. When an item is passed as a parameter to it, it will return a boolean value determining whether its hierarchy is expanded or not.

Example 5: Call the IsExpanded method of RadGridView

bool isExpanded = this.clubsGrid.IsExpanded(this.clubsGrid.Items[0]); 
Dim isExpanded As Boolean = Me.clubsGrid.IsExpanded(Me.clubsGrid.Items(0)) 

Style the Hierarchy Expand Button

RadGridView exposes the HierarchyExpandButtonStyle and HierarchyExpandButtonStyleSelector properties which allow you to (conditionally) style the toggle button displayed for expanding the hierarchy rows. The style provided for the properties needs to target the GridViewToggleButton type.

Examples 6,7 and 8 demonstrate how to set up and use the HierarchyExpandButtonStyleSelector property. Alternatively, you can define a style similar to the ones displayed in Example 7 and set it as the HierarchyExpandButtonStyle of the control.

Example 6: Defining the StyleSelector for the expand button

public class MyHierarchyExpandButtonStyleSelector : System.Windows.Controls.StyleSelector 
{ 
    public Style BigStadiumStyle { get; set; } 
    public Style SmallStadiumStyle { get; set; } 
 
    public override Style SelectStyle(object item, DependencyObject container) 
    { 
        if (item is Club) 
        { 
            Club club = item as Club; 
            if (club.StadiumCapacity > 50000) 
            { 
                return BigStadiumStyle; 
            } 
            else 
            { 
                return SmallStadiumStyle; 
            } 
        } 
        return null; 
    } 
} 
Public Class MyHierarchyExpandButtonStyleSelector 
    Inherits System.Windows.Controls.StyleSelector 
 
    Public Property BigStadiumStyle() As Style 
    Public Property SmallStadiumStyle() As Style 
 
    Public Overrides Function SelectStyle(ByVal item As Object, ByVal container As DependencyObject) As Style 
        If TypeOf item Is Club Then 
            Dim club As Club = TryCast(item, Club) 
            If club.StadiumCapacity > 50000 Then 
                Return BigStadiumStyle 
            Else 
                Return SmallStadiumStyle 
            End If 
        End If 
        Return Nothing 
    End Function 
End Class 

Example 7: Adding the style selector as a resource

    <Application.Resources> 
        <local:MyHierarchyExpandButtonStyleSelector x:Key="StadiumCapacityStyleSelector"> 
            <local:MyHierarchyExpandButtonStyleSelector.BigStadiumStyle> 
                <!-- If you're using the NoXaml binaries you need to add the following attribute to the style: 
                BasedOn="{StaticResource GridViewToggleButtonStyle}" --> 
                <Style TargetType="telerik:GridViewToggleButton"> 
                    <Setter Property="Background" Value="Red"/> 
                </Style> 
            </local:MyHierarchyExpandButtonStyleSelector.BigStadiumStyle> 
            <local:MyHierarchyExpandButtonStyleSelector.SmallStadiumStyle> 
                <!-- If you're using the NoXaml binaries you need to add the following attribute to the style: 
                BasedOn="{StaticResource GridViewToggleButtonStyle}" --> 
                <Style TargetType="telerik:GridViewToggleButton"> 
                    <Setter Property="Background" Value="Yellow" /> 
                </Style> 
            </local:MyHierarchyExpandButtonStyleSelector.SmallStadiumStyle> 
        </local:MyHierarchyExpandButtonStyleSelector> 
    </Grid.Resources> 

Example 8: Setting the HierarchyExpandButtonStyleSelector property

<telerik:RadGridView HierarchyExpandButtonStyleSelector="{StaticResource StadiumCapacityStyleSelector}"> 
<!-- ... --> 

Figure 1: RadGridView with the custom HierarchyExpandButtonStyleSelector applied

RadGridView with the custom HierarchyExpandButtonStyleSelector applied

See Also

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