Thursday, September 2, 2010

Ajax AutoComplete in ASP.Net

Without using AjaxControlToolKit we can implement AutoComplete Extender using pure Ajax Call. This article is explaining how to do make AutoComplete Extender.
OnKeyUp event help you to fetch data from Database with Ajax call. Here one Handler.ashx handles the AJAX request form Client. I add a Class file to handle database operations to better coding practice. Below I am explaining the database helper Class. Class have one method GetTable(string sqlQuery) this return DataTable after fetching data from database. And also include Provide Class, this Class help to get SqlConnection string.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.SqlClient;
using System.Configuration;
using System.Data;
/// Summary description for DBHelper
public class DBHelper
    SqlConnection connection;
    SqlDataAdapter adapter;
    SqlCommand command;
    DataTable dataTable;
    public DBHelper()
    /// passing SQL Query here/// DataTable object is returned
    public DataTable GetTable(string sqlQuery)
        //creating new instance of Datatable
        dataTable = new DataTable();
        connection = Provider.GetConnection();
        command = new SqlCommand(sqlQuery, connection);
        //Open SQL Connection
                adapter = new SqlDataAdapter(command);
            { }
                //Closing Sql Connection 
        return dataTable;
public class Provider
    public static SqlConnection GetConnection()
        //creating SqlConnection
        return new SqlConnection(ConfigurationManager.AppSettings["sqlConn"]);

Now we can look into Handler file. When request come from Ajax Call from Client it passes the data into our Database helper Class, handler file hold the data in DataTable. Result data are formatted in a table and write in the context. We can add JavaScript function for select the data, here api_helper.AddtoTaxtBox(selectedItem)is managing client section of data. Check Handler file

<%@ WebHandler Language="C#" Class="Handler" %>
using System;
using System.Web;
using System.Data;
public class Handler : IHttpHandler {
    public void ProcessRequest (HttpContext context) {

        HttpRequest request = HttpContext.Current.Request;
        //checking string null or empty
        if (!string.IsNullOrEmpty(request.QueryString["name"]))
            string name=request.QueryString["name"];
            //creating instance of new database helper
            DBHelper objDBHelper = new DBHelper();
            //creating Sql Query
            string sqlQuery = string.Format("SELECT Name FROM User WHERE Name LIKE '{0}%'", name);
            //filling data from database
            DataTable dataTable = objDBHelper.GetTable(sqlQuery);

            string table = string.Empty;
            //table for hold data
            table = "";             string td = string.Empty;             //checking datatable                 if (dataTable.Rows.Count > 0)                 {                     for (int i = 0; i < dataTable.Rows.Count; i++)
                        //adding table rows
                        td += string.Format("
", dataTable.Rows[i][0].ToString());                     }                 }                 table += td + "
"; context.Response.Write(table); } } public bool IsReusable { get { return false; } } }

Now we can check how Ajax works. On Textbox onKeyUp event call the ajax code. It send the entered value into server using ajax and result displayed in div control under the search textbox.

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">

<html xmlns="">
<head runat="server">

<style type="text/css">
      #myDiv{position:relative;top: -1px; left: 0px;width:150px; overflow:hidden;}

<form id="form1" runat="server">

<asp:TextBox ID="txtName" runat="server" onkeyup="api_helper.callAjax();"></asp:TextBox>
<div id="myDiv"></div>

<script language="javascript" type="text/javascript">

            if (typeof (api_helper) == 'undefined') { api_helper = {} }

            api_helper.doAjax = function(HandlerUrl, displayDiv) {
                var Req; try { Req = new XMLHttpRequest(); } catch (e) { try { Req = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { return false; } } } Req.onreadystatechange = function() { if (Req.readyState == 4) { var d = document.getElementById(displayDiv); d.innerHTML = Req.responseText; } }
      "GET", HandlerUrl, true); Req.send(null);

            api_helper.callAjax = function() {
                var text = document.getElementById("txtName").value;
                if (text != "") {
                    var requestUrl = "Handler.ashx?name=" + text;
                    var displayDiv="myDiv";
                    api_helper.doAjax(requestUrl, displayDiv);

            api_helper.AddtoTaxtBox = function(txt) {
                document.getElementById("txtName").value = txt;
                document.getElementById("myDiv").innerHTML = "";

Thanks for reading this article and feel free to comment.
Tags Ajax AutoComplete, Ajax Example.

1 comment:

saidwin said...

I'll Test this for the result