Data Binding Overview
RadMenu supports binding to various types of data sources:
ASP 2.0 DataSource types including
To bind the menu to a data source, specify the data source as the value of the DataSource property and call the DataBind method. If you are using declarative data sources such as AccessDataSource or SiteMapDataSource, use the DataSourceID property instead of the DataSource property.
Usually, you also want to do one or more of the following:
Set Text, Value or NavigateUrl properties using:
DataTextField - specifies the field of the data source that provides the Text of the menu items. If this field does not contain string values, you can use the DataTextFormatString property to ensure that field values are formatted the way you want.
DataValueField - Specifies the field of the data source that provides the Value of the menu items
DataNavigateUrlField - Specifies the field of the data source that provides the NavigateUrl of the menu items.
If the data source is not hierarchical, you can establish the hierarchy through an ID to ParentID relationship using:
DataFieldID - The name of the field in the data source that acts as a key, uniquely identifying rows.
DataFieldParentID - The name of the field in the data source that identifies the key field value of the parent item. The value of this field for root items should be null(table- or object-based data source) or the default value of the corresponding value type used (object-based data source).
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If the data source contains fields that map to other properties of menu items or to custom attributes, use the ItemDataBound event to set those values:
C#
protected void RadMenu1_ItemDataBound(object sender, Telerik.Web.UI.RadMenuEventArgs e) { e.Item.ToolTip = "Read more about " + (string)DataBinder.Eval(e.Item.DataItem, "Text"); }VB.NET
Protected Sub RadMenu1_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadMenuEventArgs) Handles RadMenu1.ItemDataBound e.Item.ToolTip = "Read more about " + _ CStr(DataBinder.Eval(e.Item.DataItem, "Text")) End Sub As an alternative to using the ItemDataBound event handler, you can use DataBindings to declaratively map fields from the data source to properties of menu items. The DataBindings collection also lets you map fields differently, based on the level of items.
Hierarchical data
Typically, menus are hierarchical in structure. That is, they contain child menu items that are accessed through parent menu items. RadMenu reconstructs this hierarchy differently, depending on the type of data source:
For inherently hierarchical data sources, RadMenu will automatically creates the menu item hierarchy. Such data sources include
XmlDataSource
SiteMapDataSource
For table-structured data sources, RadMenu uses the ID to ParentID relationship to establish a hierarchy. Such data sources include
DataSet, DataTable, and DataView
SqlDataSource
AccessDataSource
For object-based data sources, RadMenu uses the ID to ParentID relationship to establish a hierarchy. Such data sources include
ObjectDataSource
LinqDataSource
Any class that implements the IEnumerable interface such as List, Array, ArrayList, etc.
Appending Data Bound Items
RadMenu exposes the AppendDataBoundItems property (False by default). If you bind the menu using the DataBind method, all menu items are automatically cleared.
Setting AppendDataBoundItems to True preserves the items that are already present in the menu. This lets you bind RadMenu to multiple data sources or use both unbound and bound modes.
Binding depth
RadMenu exposes the MaxDataBindDepth property. This property is used to determine the binding depth. If for example you want to bind only the first two levels of the menu, you should set this property to 2. The default value of the MaxDataBindDepth property is -1, which means that all items will be bound. Marking the menu instance with MaxDataBindDepth="0" will NOT bind any items.
Using Templates with Data-bound Items
You can use templates with a data-bound menu. To bind template items to column values, use DataBinder.Eval expressions in the template's definition:
<%# DataBinder.Eval(Container.DataItem, "ColumnName") %>
Note that you use Container.DataItem to access the menu item when it is in a bound mode. The menu item must already be bound before template binding can work.
For live examples of data-binding RadMenu, see Declarative Data Sources and Hierarchical Data Binding.