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RadControls for ASP.NET AJAX Fundamentals
RadControls
RadAjax
RadAsyncUpload
RadBarcode
RadButton
RadCalendar
RadCaptcha
RadChart
RadColorPicker
RadComboBox
RadDataPager
RadDock
RadEditor
RadFileExplorer
RadFilter
RadFormDecorator
RadGrid
RadHtmlChart
RadImageEditor
RadInput
RadListBox
RadListView
RadMenu
RadNotification
RadODataDataSource
RadOrgChart
RadPanelBar
RadRating
RadRibbonBar
RadRotator
RadScheduler
RadScriptManager
RadSitemap
RadSlider
RadSocialShare
RadSpell
RadSplitter
RadStylesheetManager
RadTabStrip
RadTagCloud
RadToolBar
RadToolTip
RadTreeList
RadTreeView
RadUpload
RadWindow
RadXmlHttpPanel
Visual Studio Extensions
Integrating RadControls in ASPNET MVC
Integrating RadControls in DNN
Integrating RadControls in Mono
Integrating RadControls in SharePoint
API Reference
For More Help
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      RadControls for ASP.NET AJAX
Instead of supplying an ItemsRequested event handler to add items on demand to RadComboBox,
you can use a Web service to service the items request.
The path to the Web service and the name of the service method are specified in the
WebServiceSettings' Path and Method properties:
 Note |
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RadComboBox input's Text can be obtained from the context object used by the WebService's method.
The context object should be cast to IDictionary type, first.
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 CopyC# public RadComboBoxItemData[] GetProducts(object context)
{
IDictionary<string, object> contextDictionary = (IDictionary<string, object>)context;
contextDictionary["Text"].ToString();
contextDictionary["FilterString"].ToString();
}
public RadComboBoxData GetCompanyNames(RadComboBoxContext context)
{
var comboText = context.Text;
}CopyASPX <script type="text/javascript">
function OnClientItemsRequesting(sender, eventArgs) {
var context = eventArgs.get_context();
context["FilterString"] = eventArgs.get_text();
}
</script>
<telerik:radcombobox
runat="server"
id="RadComboBox1"
width="300px"
enableloadondemand="true"
onclientitemsrequesting="OnClientItemsRequesting">
<WebServiceSettings Method="GetProducts" Path="Products.asmx" />
</telerik:radcombobox>To use the integrated support, the Web service should have the following signature: CopyC# [WebMethod]
public RadComboBoxItemData[] GetProducts(object context)
{
IDictionary<string, object> contextDictionary = (IDictionary<string, object>)context;
SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString);
string filterString = ((string)contextDictionary["FilterString"]).ToLower();
SqlCommand selectCommand = new SqlCommand(
@" SELECT * FROM Customers WHERE LOWER(CompanyName) LIKE '" + filterString + "%'", connection);
SqlDataAdapter adapter = new SqlDataAdapter(selectCommand);
DataTable products = new DataTable();
adapter.Fill(products);
List<RadComboBoxItemData> result = new List<RadComboBoxItemData>(products.Rows.Count);
foreach (DataRow row in products.Rows)
{
RadComboBoxItemData itemData = new RadComboBoxItemData();
itemData.Text = row["CompanyName"].ToString();
itemData.Value = row["CompanyName"].ToString();
result.Add(itemData);
}
return result.ToArray();
}
[WebMethod]
public RadComboBoxData GetCompanyNames(RadComboBoxContext context)
{
string sql = "SELECT * from Customers WHERE CompanyName LIKE '" + context.Text + "%'";
SqlDataAdapter adapter = new SqlDataAdapter(sql, ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString);
DataTable data = new DataTable(); adapter.Fill(data);
List<RadComboBoxItemData> result = new List<RadComboBoxItemData>(context.NumberOfItems);
RadComboBoxData comboData = new RadComboBoxData();
try
{
int itemsPerRequest = 10;
int itemOffset = context.NumberOfItems;
int endOffset = itemOffset + itemsPerRequest;
if (endOffset > data.Rows.Count)
{
endOffset = data.Rows.Count;
}
if (endOffset == data.Rows.Count)
{
comboData.EndOfItems = true;
}
else
{
comboData.EndOfItems = false;
}
result = new List<RadComboBoxItemData>(endOffset - itemOffset);
for (int i = itemOffset; i < endOffset; i++)
{
RadComboBoxItemData itemData = new RadComboBoxItemData();
itemData.Text = data.Rows[i]["CompanyName"].ToString();
itemData.Value = data.Rows[i]["CompanyName"].ToString();
result.Add(itemData);
}
if (data.Rows.Count > 0)
{
comboData.Message = String.Format("Items <b>1</b>-<b>{0}</b> out of <b>{1}</b>", endOffset.ToString(), data.Rows.Count.ToString());
}
else
{
comboData.Message = "No matches";
}
}
catch (Exception e)
{
comboData.Message = e.Message;
}
comboData.Items = result.ToArray();
return comboData;
}CopyVB.NET <WebMethod()>
Public Function GetProducts(ByVal context As Object) As RadComboBoxItemData()
Dim contextDictionary As IDictionary(Of String, Object) = DirectCast(context, IDictionary(Of String, Object))
Dim connection As New SqlConnection(ConfigurationManager.ConnectionStrings("NorthwindConnectionString").ConnectionString)
Dim filterString As String = (DirectCast(contextDictionary("FilterString"), String)).ToLower()
Dim selectCommand As New SqlCommand("" & Chr(9) &
"SELECT * FROM Customers" & Chr(13) & "" & Chr(10) & + filterString + , connection)
Dim adapter As New SqlDataAdapter(selectCommand)
Dim products As New DataTable()
adapter.Fill(products)
Dim result As New List(Of RadComboBoxItemData)(products.Rows.Count)
For Each row As DataRow In products.Rows
Dim itemData As New RadComboBoxItemData()
itemData.Text = row("CompanyName").ToString()
itemData.Value = row("CompanyName").ToString()
result.Add(itemData)
Next
Return result.ToArray()
End Function
<WebMethod()>
Public Function GetCompanyNames(ByVal context As RadComboBoxContext) As RadComboBoxData
Dim sql As String = + context.Text +
Dim adapter As New SqlDataAdapter(sql, ConfigurationManager.ConnectionStrings("NorthwindConnectionString").ConnectionString)
Dim data As New DataTable()
adapter.Fill(data)
Dim result As New List(Of RadComboBoxItemData)(context.NumberOfItems)
Dim comboData As New RadComboBoxData()
Try
Dim itemsPerRequest As Integer = 10
Dim itemOffset As Integer = context.NumberOfItems
Dim endOffset As Integer = itemOffset + itemsPerRequest
If endOffset > data.Rows.Count Then
endOffset = data.Rows.Count
End If
If endOffset = data.Rows.Count Then
comboData.EndOfItems = True
Else
comboData.EndOfItems = False
End If
result = New List(Of RadComboBoxItemData)(endOffset - itemOffset)
Dim i As Integer = itemOffset
While i < endOffset
Dim itemData As New RadComboBoxItemData()
itemData.Text = data.Rows(i)("CompanyName").ToString()
itemData.Value = data.Rows(i)("CompanyName").ToString()
result.Add(itemData)
i = i + 1
End While
If data.Rows.Count > 0 Then
comboData.Message = [String].Format("Items <b>1</b>-<b>{0}</b> out of <b>{1}</b>", endOffset.ToString(), data.Rows.Count.ToString())
Else
comboData.Message = "No matches"
End If
Catch e As Exception
comboData.Message = e.Message
End Try
comboData.Items = result.ToArray()
Return comboData
End FunctionFor a live example refer to the online demo: Populate From Web Service. See Also
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