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Binding to Object-Based Data Sources

You can bind RadMenu to an object-based data source such as ObjectDataSource, LinqDataSource or any class that implements the IEnumerable interface.

Binding to ObjectDataSource

note

To see this type of data binding in action, please visit the Declarative Data Sources live demo.

When using ObjectDataSource, you can bind RadMenu declaratively at design time. The SelectMethod of the ObjectDataSource should return an object that supports the IEnumerable or ICollection interface. Such collections include Array, ArrayList, and List.

If the SelectMethod returns a collection of strings, those strings are automatically mapped to the Text property of the respective menu items. If the collection contains objects (as opposed to string values), you can use the DataTextField, DataNavigateUrlField, and the DataValueField properties to map a property from the object directly to the Text, NavigateUrl and Value properties of RadMenuItem. If the DataFieldID and DataFieldParentID properties are set, RadMenu will create a hierarchy of Items, determining the Root ones using the following algorithm:

note
  • their DataFieldParentID property must be null if it is of nullable (e.g. int? ) or reference (e.g. string ) type. -example:- ID ParentID 1 (null) 2 1
    • their DataFieldParentID property must return the default value if it is value type (e.g. 0 for int , Guid.Empty for Guid ). -example:- ID ParentID 1 0 2 1

To map additional properties from the object to other properties of the respective menu item, use an ItemDataBound event handler. The event arguments passed to the event, e.Item and e.Item.DataItem, hold the instance of the menu item being bound and the DataItem associated with the menu item. You can map a property from the DataItem to the property of the RadMenuItem class (make sure to cast the DataItem object to your respective data type first).

The following example shows a RadMenu bound declaratively to an ObjectDataSource:

<telerik:RadMenu RenderMode="Lightweight" ID="RadMenu1" runat="server" Flow="Horizontal" DataSourceID="ObjectDataSource1">
</telerik:RadMenu>
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="GetSiteData"
    TypeName="SiteDataItem">
</asp:ObjectDataSource>

The ObjectDataSource component is configured to use the SiteDataItem business object. The SiteDataItem class is defined below:

using System.Collections.Generic;

public class SiteDataItem{ 
    private string _text; 
    private string _url; 
    private int _id; 
    private int _parentId;

    public string Text
    {  
        get 
        { 
            return _text; 
        }  
        set 
        { 
            _text = value;
        } 
    }

    public string Url 
    {  
        get 
        { 
            return _url; 
        }  
        set 
        { 
            _url = value;
        } 
    }
    public int ID 
    {  
        get 
        { 
            return _id;
        }  
        set 
        { 
            _id = value;
        } 
    }
    public int ParentID 
    {  
        get 
        { 
            return _parentId;
        } 
        set 
        { 
            _parentId = value;
        } 
    }
    public SiteDataItem(int id, int parentId, string text, string url)
    {  
        _id = id;
        _parentId = parentId;
        _text = text;
        _url = url;
    }

    public static List<SiteDataItem> GetSiteData() 
    {  
        List<SiteDataItem> siteData = new List<SiteDataItem>();
        siteData.Add(new SiteDataItem(1, 0, "All Sites", ""));  
        siteData.Add(new SiteDataItem(2, 1, "Search Engines", ""));
        siteData.Add(new SiteDataItem(3, 1, "News Sites", ""));
        siteData.Add(new SiteDataItem(4, 2, "Yahoo", "http://www.yahoo.com"));
        siteData.Add(new SiteDataItem(5, 2, "MSN", "http://www.msn.com"));  
        siteData.Add(new SiteDataItem(6, 2, "Google", "http://www.google.com"));  
        siteData.Add(new SiteDataItem(7, 3, "CNN", "http://www.cnn.com"));  
        siteData.Add(new SiteDataItem(8, 3, "BBC", "http://www.bbc.co.uk"));  
        siteData.Add(new SiteDataItem(9, 3, "FOX", "http://www.foxnews.com"));
        return siteData; 
    }
}       
Imports System.Collections.Generic
Public Class SiteDataItem
    Private _text As String
    Private _url As String
    Private _id As Integer
    Private _parentId As Integer
    Public Property Text() As String
        Get
            Return _text
        End Get
        Set(ByVal value As String)
            _text = value
        End Set
    End Property
    Public Property Url() As String
        Get
            Return _url
        End Get
        Set(ByVal value As String)
            _url = value
        End Set
    End Property
    Public Property ID() As Integer
        Get
            Return _id
        End Get
        Set(ByVal value As Integer)
            _id = value
        End Set
    End Property
    Public Property ParentID() As Integer
        Get
            Return _parentId
        End Get
        Set(ByVal value As Integer)
            _parentId = value
        End Set
    End Property
    Public Sub New(ByVal id As Integer, ByVal parentId As Integer, ByVal text As String, ByVal url As String)
        _id = id
        _parentId = parentId
        _text = text
        _url = url
    End Sub
    Public Shared Function GetSiteData() As List(Of SiteDataItem)
        Dim siteData As New List(Of SiteDataItem)()
        siteData.Add(New SiteDataItem(1, 0, "All Sites", ""))
        siteData.Add(New SiteDataItem(2, 1, "Search Engines", ""))
        siteData.Add(New SiteDataItem(3, 1, "News Sites", ""))
        siteData.Add(New SiteDataItem(4, 2, "Yahoo", "http://www.yahoo.com"))
        siteData.Add(New SiteDataItem(5, 2, "MSN", "http://www.msn.com"))
        siteData.Add(New SiteDataItem(6, 2, "Google", "http://www.google.com"))
        siteData.Add(New SiteDataItem(7, 3, "CNN", "http://www.cnn.com"))
        siteData.Add(New SiteDataItem(8, 3, "BBC", "http://www.bbc.co.uk"))
        siteData.Add(New SiteDataItem(9, 3, "FOX", "http://www.foxnews.com"))
        Return siteData
    End Function
End Class

Binding to an object that implements IEnumerable

note

To see this type of data binding in action, please visit the Hierarchical Data Binding live demo.

Instead of going through an ObjectDataSource, you can bind RadMenu directly to any collection that implements the ICollection or IEnumerable interface.Mapping properties of the objects in the collection to properties of the menu items works exactly the same way as when using ObjectDataSource.

To bind directly to a collection, you must bind the menu at runtime, using the following steps:

  1. Create the collection.

  2. Add items to the collection. Depending on the type of the collection, these can be strings, or more complex objects with properties that provide data for the various properties of RadMenuItem and/or for the ID -> ParentID relationship.

  3. Set the DataSource property of RadMenu to the instance of the collection.

  4. Call the DataBind method.

The following example shows a menu bound to an ArrayList. The list contains SiteDataItem objects with the same definition as in the ObjectDataSource example, only that their ParentID property is of nullable type - int?:

private ArrayList GenerateSiteData()
{  
    ArrayList siteData = new ArrayList();  
    siteData.Add(new SiteDataItem(1, null, "All Sites", ""));  
    siteData.Add(new SiteDataItem(2, 1, "Search Engines", "")); 
    siteData.Add(new SiteDataItem(3, 1, "News Sites", "")); 
    siteData.Add(new SiteDataItem(4, 2, "Yahoo", "http://www.yahoo.com"));  
    siteData.Add(new SiteDataItem(5, 2, "MSN", "http://www.msn.com"));  
    siteData.Add(new SiteDataItem(6, 2, "Google", "http://www.google.com"));  
    siteData.Add(new SiteDataItem(7, 3, "CNN", "http://www.cnn.com"));  
    siteData.Add(new SiteDataItem(8, 3, "BBC", "http://www.bbc.co.uk"));
    siteData.Add(new SiteDataItem(9, 3, "FOX", "http://www.foxnews.com"));
    return siteData;
}
protected void Page_Load(object sender, EventArgs e)
{  
    if (!IsPostBack)
    {    
        RadMenu1.DataTextField = "Text";
        RadMenu1.DataNavigateUrlField = "Url";
        RadMenu1.DataFieldID = "ID";    
        RadMenu1.DataFieldParentID = "ParentID";    
        RadMenu1.DataSource = GenerateSiteData();    
        RadMenu1.DataBind();  
    }
}   
Private Function GenerateSiteData() As ArrayList
    Dim siteData As New ArrayList()
    siteData.Add(New SiteDataItem(1, Nothing, "All Sites", ""))
    siteData.Add(New SiteDataItem(2, 1, "Search Engines", ""))
    siteData.Add(New SiteDataItem(3, 1, "News Sites", ""))
    siteData.Add(New SiteDataItem(4, 2, "Yahoo", "http://www.yahoo.com"))
    siteData.Add(New SiteDataItem(5, 2, "MSN", "http://www.msn.com"))
    siteData.Add(New SiteDataItem(6, 2, "Google", "http://www.google.com"))
    siteData.Add(New SiteDataItem(7, 3, "CNN", "http://www.cnn.com"))
    siteData.Add(New SiteDataItem(8, 3, "BBC", "http://www.bbc.co.uk"))
    siteData.Add(New SiteDataItem(9, 3, "FOX", "http://www.foxnews.com"))
    Return siteData
End Function

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Not IsPostBack Then
        RadMenu1.DataTextField = "Text"
        RadMenu1.DataNavigateUrlField = "Url"
        RadMenu1.DataFieldID = "ID"
        RadMenu1.DataFieldParentID = "ParentID"
        RadMenu1.DataSource = GenerateSiteData()
        RadMenu1.DataBind()
    End If
End Sub

See Also