Passing Additional Information to the Server

When using RadSearchBox it can often be useful to pass additional information to the server to improve its performance or to set some specific condition. This can easily be achieved in the OnClientDataRequesting event by using the userContext object, which is of type IDictionary, and setting its KeyValue parameters. After that this object is passed to the server along with the search request and is available in the OnDataSourceSelect event handler or to the Web Service that searches items to the RadSearchBox.

Use the get_maxResultCount() client-side method to pass the number of items the response should return.

Using Additional userContext information with a WebService

This example below demonstrates how you can pass an integer value to the Web Service method through the OnClientDataRequesting event that will limit your search operation so that only the items that are with smaller ‘UnitPrice’ than the passed one are returned:

<script type="text/javascript">
    function OnClientDataRequesting(sender, args) {
        args.get_userContext()["maxUnitPrice"] = 10;
    }
</script>
<telerik:RadSearchBox RenderMode="Lightweight" runat="server" id="RadSearchBox4"
    onclientdatarequesting="OnClientDataRequesting">
    <DropDownSettings Height="400" Width="300" />
    <WebServiceSettings Path="SearchBox.aspx" Method="GetResults" />
</telerik:RadSearchBox>

[WebMethod]
public static SearchBoxItemData[] GetResults(SearchBoxContext context)
{
    int unitPrice = (int)context.UserContext["maxUnitPrice"];
    List<SearchBoxItemData> result = new List<SearchBoxItemData>();
    DataTable data = GetData(context.Text, unitPrice);
    for (int i = 0; i < data.Rows.Count; i++)
    {
        SearchBoxItemData itemData = new SearchBoxItemData();
        itemData.Text = data.Rows[i]["ProductName"].ToString();
        itemData.Value = data.Rows[i]["ProductId"].ToString();
    }
    return result.ToArray();
}

private static DataTable GetData(string filterString, int unitPrice)
{
    SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString);
    SqlCommand command = new SqlCommand("SELECT [ProductId], [ProductName],[UnitPrice] FROM [Products] WHERE [ProductName] LIKE '%' + @filterString + '%' AND [UnitPrice] <=@unitPrice ORDER BY [ProductId]");
    command.Parameters.AddWithValue("@filterString", filterString);
    command.Parameters.AddWithValue("@unitPrice", unitPrice);
    command.Connection = connection;
    SqlDataAdapter adapter = new SqlDataAdapter(command);
    DataTable data = new DataTable();
    adapter.Fill(data);
    return data;
}

<WebMethod> _
Public Shared Function GetResults(context As SearchBoxContext) As SearchBoxItemData()
    Dim unitPrice As Integer = CInt(context.UserContext("maxUnitPrice"))
    Dim result As New List(Of SearchBoxItemData)()
    Dim data As DataTable = GetData(context.Text, unitPrice)
    For i As Integer = 0 To data.Rows.Count - 1
        Dim itemData As New SearchBoxItemData()
        itemData.Text = data.Rows(i)("ProductName").ToString()
        itemData.Value = data.Rows(i)("ProductId").ToString()
    Next
    Return result.ToArray()
End Function

Private Shared Function GetData(filterString As String, unitPrice As Integer) As DataTable
    Dim connection As New SqlConnection(ConfigurationManager.ConnectionStrings("NorthwindConnectionString").ConnectionString)
    Dim command As New SqlCommand("SELECT [ProductId], [ProductName],[UnitPrice] FROM [Products] WHERE [ProductName] LIKE '%' + @filterString + '%' AND [UnitPrice] <=@unitPrice ORDER BY [ProductId]")
    command.Parameters.AddWithValue("@filterString", filterString)
    command.Parameters.AddWithValue("@unitPrice", unitPrice)
    command.Connection = connection
    Dim adapter As New SqlDataAdapter(command)
    Dim data As New DataTable()
    adapter.Fill(data)
    Return data
End Function

Using Additional userContext information with the OnDataSourceSelect event

In the example below it is explained how to achieve the same scenario by passing information to the OnDataSourceSelect server event:

<script type="text/javascript">
   function OnClientDataRequesting(sender, args) {
       args.get_userContext()["maxUnitPrice"] = 10;
   }
</script>
<telerik:RadSearchBox RenderMode="Lightweight" ID="RadSearchBox1" runat="server" Width="500"
    DropDownSettings-Height="200px"
    OnClientDataRequesting="OnClientDataRequesting" DataSourceID="SqlDataSource1" 
    DataTextField="ProductName" DataValueField="ProductID" 
    OnDataSourceSelect="RadSearchBox1_DataSourceSelect">
</telerik:RadSearchBox>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
    ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
    SelectCommand="SELECT [ProductId], [ProductName],[UnitPrice] FROM [Products]">
</asp:SqlDataSource>

protected void RadSearchBox1_DataSourceSelect(object sender, SearchBoxDataSourceSelectEventArgs e)
{
    SqlDataSource source = (SqlDataSource)e.DataSource;
    RadSearchBox searchBox = (RadSearchBox)sender;
    string likeCondition = string.Format("'{0}{1}%'", searchBox.Filter == SearchBoxFilter.Contains ? "%" : "", e.FilterString);
    string unitPrice = e.UserContext["maxUnitPrice"].ToString();
    source.SelectCommand = "SELECT * FROM[Products] WHERE [" + searchBox.DataTextField + "] LIKE " + likeCondition + "AND [UnitPrice] <=" + unitPrice;
}

Protected Sub RadSearchBox1_DataSourceSelect(sender As Object, e As SearchBoxDataSourceSelectEventArgs)
    Dim source As SqlDataSource = DirectCast(e.DataSource, SqlDataSource)
    Dim searchBox As RadSearchBox = DirectCast(sender, RadSearchBox)
    Dim likeCondition As String = String.Format("'{0}{1}%'", If(searchBox.Filter = SearchBoxFilter.Contains, "%", ""), e.FilterString)
    Dim unitPrice As String = e.UserContext("maxUnitPrice").ToString()
    source.SelectCommand = "SELECT * FROM[Products] WHERE [" + searchBox.DataTextField + "] LIKE " + likeCondition + "AND [UnitPrice] <=" + unitPrice
End Sub