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MenuItemBinding Class

Note: This class is new in the .NET Framework version 2.0.

Defines the relationship between a data item and the menu item it is binding to in a Menu control. This class cannot be inherited.

Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)

public sealed class MenuItemBinding : IStateManager, ICloneable, IDataSourceViewSchemaAccessor
public final class MenuItemBinding implements IStateManager, ICloneable, 
	IDataSourceViewSchemaAccessor
public final class MenuItemBinding implements IStateManager, ICloneable, 
	IDataSourceViewSchemaAccessor

When the Menu control is bound to a data source where each data item contains multiple fields (such as an XML element with several attributes), if no menu item bindings are defined, a menu item displays the value returned by the ToString() method of the data item by default. In the case of an XML element, the menu item displays the element name, which shows the underlying structure of the menu, but is not very useful otherwise. You can bind the properties of a menu item to a specific field by specifying menu item bindings. A MenuItemBinding object defines the relationship between each data item and the menu item it is binding to.

NoteNote

When the Menu control is bound to a SiteMapDataSource control, menu item bindings have no effect. Binding is performed automatically using the site map provider.

The Menu control stores its MenuItemBinding objects in the DataBindings property and applies the bindings to the data source to create a one-to-one relationship between the menu hierarchy and the data source hierarchy. For each data item in the data source, the Menu control attempts to match the data item to a MenuItemBinding object to create the corresponding MenuItem object.

When creating a MenuItemBinding object, you must specify the criteria for binding. The criteria indicate when a data item should be bound to a menu item. You can specify the Depth, the DataMember, or both.

A menu item depth specifies the menu level that gets bound. For example, the following MenuItemBinding declaration binds the Name and ID fields of the data source to the Text and Value properties, respectively, of all nodes with a depth of 0:

<asp:MenuItemBinding Depth="0" TextField="Name" ValueField="ID">

A data member specifies the type of the data item in the underlying data source, but can represent different information depending on the data source. Each data item in a hierarchical data source (represented by an IHierarchyData object) exposes a Type property, which specifies the type of the data item. For example, the data member for an XML element specifies the name of the element. When a data source contains multiple data item types, the data member specifies which data item type to use. The following MenuItemBinding declaration binds the <Book> elements of an XmlDataSource control to all the menu items in the menu, regardless of the location in the hierarchy:

<asp:MenuItemBinding DataMember="Book" TextField="Title" ValueField= "ISBN">

Sometimes you might need to create a menu item binding that specifies both a depth and a data member. This is often used when the data source contains items at different levels that have the same data member value. For example, you can have <Item> elements that appear at different levels within an XML file. The following MenuItemBinding declarations show how to specify menu item bindings that apply to identical data members at different menu depths:

<asp:MenuItemBinding DataMember="Item" Depth="1" TextField="Title">

<asp:MenuItemBinding DataMember="Item" Depth="2" TextField="ISBN">

If a menu item binding is defined without a depth and a data member, the menu item binding is applied to all menu items within the menu. This is commonly used when all data items have the same properties and should be displayed identically, regardless of the menu depth.

After the binding criteria are established, you can then bind a property of a MenuItem object that can be bound to a value. You can bind to a field of a data item or to a static value. When bound to a static value, all MenuItem objects to which the MenuItemBinding object is applied share the same value. Properties bound to fields contain the values of the corresponding field from the data source.

NoteNote

You can selectively override a bound property in a MenuItem object by setting the corresponding property directly.

The following table lists the properties of the MenuItemBinding class that allow you to bind a property of the MenuItem object to a field of a data item.

Property

Description

ImageUrlField

The field to bind to the ImageUrl property of a MenuItem object.

NavigateUrlField

The field to bind to the NavigateUrl property of a MenuItem object.

TextField

The field to bind to the Text property of a MenuItem object.

ToolTipField

The field to bind to the ToolTip property of a MenuItem object.

ValueField

The field to bind to the Value property of a MenuItem object.

The following table lists the properties of the MenuItemBinding class that allow you to bind a property of the MenuItem object to a static value.

Property

Description

ImageUrl

The static value to bind to the ImageUrl property of a MenuItem object.

NavigateUrl

The static value to bind to the NavigateUrl property of a MenuItem object.

Target

The static value to bind to the Target property of a MenuItem object.

Text

The static value to bind to the Text property of a MenuItem object.

ToolTip

The static value to bind to the ToolTip property of a MenuItem object.

Value

The static value to bind to the Value property of a MenuItem object.

If conflicting MenuItemBinding objects are defined, the Menu control applies the menu item bindings in the following order of precedence:

  1. The MenuItemBinding object that defines and matches both a depth and a data member.

  2. The MenuItemBinding object that defines and matches the data member only.

  3. The MenuItemBinding object that defines and matches the depth only.

  4. The MenuItemBinding object that defines neither the depth nor the data member. (This type of menu item binding is applied to all menu items in the menu.)

  5. The MenuItemBinding object that does not have a match in the data source. In this case, the value returned by the ToString() method of the data item is then bound to the Text and Value properties of the menu items to which the MenuItemBinding object is applied.

The MenuItemBinding class also allows you to format the text displayed in a menu item by setting the FormatString property.

TopicLocation
Walkthrough: Displaying a Menu on Web PagesBuilding ASP .NET Web Applications in Visual Studio
Walkthrough: Controlling ASP.NET Menus ProgrammaticallyBuilding ASP .NET Web Applications in Visual Studio

The following code example demonstrates how to use MenuItemBinding objects to define the relationship between the fields of an XmlDataSource control and the menu items in a Menu control. For this example to work correctly, you must copy the sample XML data below to a file named Menu.xml.


<%@ page language="C#" %>

<html>
  <body>
    <form runat="server">

      <h3>MenuItemBinding Example</h3>

      <asp:menu id="NavigationMenu"
        datasourceid="MenuSource"
        runat="server">
        
        <DataBindings>
        
          <asp:menuitembinding datamember="MapHomeNode"
            formatstring="({0})" 
            textfield="Title"
            valuefield="Description"
            imageurlfield="ImageUrl"
            tooltipfield="ToolTip"
            target="_self" />
          <asp:menuitembinding datamember="MapNode" 
            depth="1"
            formatstring="[{0}]" 
            textfield="Title"
            valuefield="Description"
            imageurlfield="ImageUrl"
            tooltipfield="ToolTip"
            target="_blank"/>
          <asp:menuitembinding datamember="MapNode" 
            depth="2"
            formatstring="<{0}>" 
            textfield="Title"
            valuefield="Description"
            imageurlfield="ImageUrl"
            tooltipfield="ToolTip"
            target="_blank"/>
          
        </DataBindings>
        
      </asp:menu>

      <asp:xmldatasource id="MenuSource"
        datafile="Menu.xml"
        runat="server"/> 

    </form>
  </body>
</html>


The following code is sample site map data for the previous example.

<MapHomeNode ImageUrl="~\Images\Home.gif"

Title="Home"

Description="Root Page"

ToolTip="Home Page">

<MapNode ImageUrl="~\Images\Music.gif"

Title="Music"

Description="Music Category"

ToolTip="Music Page">

<MapNode ImageUrl="~\Images\Classical.gif"

Title="Classical"

Description="Classical Section"

ToolTip="Classical Page"/>

<MapNode ImageUrl="~\Images\Rock.gif"

Title="Rock"

Description="Rock Section"

ToolTip="Rock Page"/>

<MapNode ImageUrl="~\Images\Jazz.gif"

Title="Jazz"

Description="Jazz Section"

ToolTip="Jazz Page"/>

</MapNode>

<MapNode ImageUrl="~\Images\Movies.gif"

Title="Movies"

Description="Movies Category"

ToolTip="Movies Page">

<MapNode ImageUrl="~\Images\Action.gif"

Title="Action"

Description="Action Section"

ToolTip="Action Page"/>

<MapNode ImageUrl="~\Images\Drama.gif"

Title="Drama"

Description="Drama Section"

ToolTip="Drama Page"/>

<MapNode ImageUrl="~\Images\Musical.gif"

Title="Musical"

Description="Musical Section"

ToolTip="Musical Page"/>

</MapNode>

</MapHomeNode>

System.Object
  System.Web.UI.WebControls.MenuItemBinding

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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