If you work in hierarchy mode, you can define when the data binding for GridTableView will occur. In order to do this, you need to set the following property:

GridTableView.HierarchyLoadMode

The possible values are:

• HierarchyLoadMode.ServerBind - all child GridTableViews will be bound immediately when DataBind occurs for a parent GridTableView or RadGrid.
• HierarchyLoadMode.ServerOnDemand - data binding of a child GridTableView will only take place when an item is expanded. This is the default value.
• HierarchyLoadMode.Client is similar to HierarchyLoadMode.ServerBind but the items are expanded client-side, using JavaScript manipulations instead of postback to the server.

In order to use client-side hierarchy expand, you will need to set also ClientSettings.AllowExpand.Collapse to true.

Changing the GridTableView.HierarchyLoadMode property value impacts the performance in the following way:

In HierarchyLoadMode.ServerBind mode:

• The roundtrip to the database happens only once - when the grid is bound.
• The ViewState holds all data for the detail tables.
• Only detail table-views for the expanded items are rendered.
• You need to postback to the server to in order to expand an item.

In HierarchyLoadMode.ServerOnDemand mode:

• The roundtrip to the database happens when the grid is bound and when an item is expanded.
• The ViewState holds data only for the visible Items (the smallest possible ViewState).
• Only detail table-views of the expanded items are rendered.
• You need to postback to the server in order to expand an item.

In HierarchyLoadMode.Client mode:

• The roundtrip to the database happens only when grid is bound.
• The ViewState holds all detail tables data.
• All items are rendered - even if not visible (not expanded).
• No postback to the server is needed to expand an item - expand/collapse of hierarchy items is managed client-side.

Note: When setting HierarchyLoadMode = Client you should also set ClientSettings -> AllowExpandCollapse = true for your grid instance.

This example shows the advanced hierarchy model of Telerik RadGrid with client-side expand/collapse. A three level hierarchy is demonstrated with Customer Master Table and two nested Detail Tables - Orders and OrderDetails. All grid levels have set GridTableView.HierarchyLoadMode.Client.