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Web Serivce return null

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TreeView

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answered on 14 Jan 2008, 08:41 AM

Hello Jason Lee,

What about returning an empty array. Is that acceptable for you?
    public RadComboBoxItemData[] GetProducts(object context)
    {
        IDictionary<string, object> contextDictionary = (IDictionary<string, object>) context;

        SqlConnection connection =
                    new SqlConnection(ConfigurationManager.ConnectionStrings["TelerikConnectionString"].ConnectionString);

        string filterString = ((string) contextDictionary["FilterString"]).ToLower();
        SqlCommand selectCommand =
            new SqlCommand(@"    SELECT ID, ProductName FROM Products
                                WHERE LOWER(ProductName) 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["ProductName"].ToString();
            itemData.Value = row["ID"].ToString();
            result.Add(itemData);
        }

        return result.ToArray();
    }

You can leave the "result" list empty.

Regards,
Nick
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answered on 24 Jan 2008, 09:15 AM

Hi Simeon,

I wasn't able to make my stuff work. Can you take a look at what I am missing here...

Im getting the message..."The server method Get_RadTreeNodeData failed"

Default.aspx
<%@ Page Language="VB" AutoEventWireup="true" CodeFile="Default.aspx.vb" Inherits="_Default" %>

<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
    <script type="text/javascript">
        function nodePopulating(sender, eventArgs)
        {
            var node = eventArgs.get_node();
            var context = eventArgs.get_context();
            context["ID"] = node.get_value();
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
                   
    </div>
        <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
        </telerik:RadScriptManager>
        <telerik:RadStyleSheetManager ID="RadStyleSheetManager1" runat="server">
        </telerik:RadStyleSheetManager>
         
        <telerik:RadTreeView ID="RadTreeView1" runat="server" CheckBoxes="True" LoadingStatusPosition="BeforeNodeText"
            Skin="Vista" OnClientNodePopulating="nodePopulating">
            <WebServiceSettings Path="http://localhost/DataService/Service.asmx" Method="Get_RadTreeNodeData" />
            <Nodes>
                <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Handsets" Value="1">
                    <Nodes>
                        <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Alcatel" Value="2">
                        </telerik:RadTreeNode>
                        <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Blackberry" Value="10">
                        </telerik:RadTreeNode>
                        <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Dopod" Value="18">
                        </telerik:RadTreeNode>
                        <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Ericsson" Value="20">
                        </telerik:RadTreeNode>
                        <telerik:RadTreeNode runat="server" ExpandMode="WebService" Text="Nokia" Value="40">
                        </telerik:RadTreeNode>
                    </Nodes>
                </telerik:RadTreeNode>
            </Nodes>
            <CollapseAnimation Duration="100" Type="OutQuint" />
            <ExpandAnimation Duration="100" Type="OutQuart" />
        </telerik:RadTreeView>
    </form>
</body>
</html>

Web Service

<WebMethod()> _
    Public Function Get_RadTreeNodeData(ByVal node As RadTreeNodeData, ByVal context As Object) As RadTreeNodeData()
        Dim _serviceOperations As New ServiceOperations
        Dim rtNodeData() As RadTreeNodeData
        rtNodeData = _serviceOperations.Get_RadTreeNodeData(context)
        Return rtNodeData
    End Function

Public Function Get_RadTreeNodeData(ByVal context As Object) As RadTreeNodeData()
        Dim contextDictionary As New Dictionary(Of String, Object)
        contextDictionary = Convert.ChangeType(context, contextDictionary.GetType)

        Dim connection As SqlConnection = New SqlConnection(_conString)
        'Dim filterString As String = Convert.ToString(contextDictionary("FilterString")).ToLower

        'Dim selectCommand As SqlCommand = New SqlCommand(" SELECT ID, Text FROM Handsets_Tree WHERE LOWER(Text) LIKE '" + filterString + "%'", connection)
        Dim selectCommand As SqlCommand = New SqlCommand(" SELECT ID, Text FROM Handsets_Tree WHERE Parent_id Is Null ", connection)
        Dim adapter As SqlDataAdapter = New SqlDataAdapter(selectCommand)
        Dim products As New DataTable
        adapter.Fill(products)

        Dim result As List(Of RadTreeNodeData) = New List(Of RadTreeNodeData)(products.Rows.Count)
        For Each row As DataRow In products.Rows
            Dim itemData As New RadTreeNodeData
            itemData.Text = Convert.ToString(row("Text"))
            itemData.Value = Convert.ToString(row("ID"))
            result.Add(itemData)
        Next
        Return result.ToArray
    End Function

answered on 01 Feb 2008, 09:28 AM

RadTreeViewWebServiceLoadOnDemand.zip

Hi jim,

Please find attached a working project demonstrating the same approach. You can compare it to yours and see the differences.

Kind regards,
Simeon
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answered on 22 May 2009, 11:41 AM

Hi subi,

Unfortunately implementing built-in support for cross domain web services is not possible. There is a built-in restriction in ASP.NET web services which disallows using of JSONP (which is the common solution to do cross domain web service requests). Workarounds do exist however they require writing a custom HTTP handler or using WCF. Still RadTreeView will not be able to automatically use that custom web service (or handler) and should be populated by hand using the client side API.

All the best,
Albert
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answered on 06 Oct 2009, 01:19 AM

Dear Friend -

First this link is not working.

Next there is need for little more explanation on the IDictionary object - used in the Web Service method. I also find a disconnect in under standing the role of java script and web service call.

Could you please correct me if i am wrong as following:

1. When the user click the + sign in the tree a JavaScript method has to be called
2. This java script method initiate the web service.
3. The web service complete the execution and returns an array (through some way - i can't figure out where and how?) of nodes and the child nodes are populated.

This is what I found through debugging. I used a OnClientNodePoppulating JS event.

looking forward to a response.