Using WebHandlers with jQuery (ASP.NET 2)

A WebHandler is a useful way for updating data without needed to resort to an ASP.NET page (with its additional overhead). You can decide what content type to send (so can send data as text/html, text/plain or even image/jpeg - all can be handled with the same file) and don't have to worry about view state, but you cannot use the WYSIWYG utilities you may normally use so they are more suited to those comfortable with coding by hand. Combine this with jQuery and you have an easy way to update records (or do any kind of processing on the server) without using postbacks (and it can result in a more efficient application).

The ASP.NET page

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
 <title>Test Page</title>

 <script src="jquery-latest.pack.js" type="text/javascript"></script>

 <script type="text/javascript">
 $(
  function()
  {
   $("input[@name$=AddRecord][@type=submit]").click(addRecord);
  }
 )
 function addRecord()
 {
  var data = $("#addcontact input[@type=text], #addcontact textarea").serialize();
  var tmp = data.split("&");
  var tmp2 = [];
  var fielddata;
  for(var f in tmp)
  {
   // $'s are used to make unique names (eg ctl00$FirstName, ctl00$MyPanel$FirstName), so it is split
   fielddata = tmp[f].split("$");
   // deliminator in .NET 1.1 is ':' so tmp[f].split(":") should hopefully work
   // get the item in the array (which is the field name and data)
   tmp2[tmp2.length] = fielddata[fielddata.length - 1];
  }
  // set new data
  data = tmp2.join("&");
  $.ajax(
   {
    type: "POST",
    url: "addrecord.ashx",
    data: data,
    success: function(msg)
    {
     alert(msg);
    }
   }
  );
  return false;
 }
 </script>

</head>
<body>
 <form runat="server">
  <div id="addcontact">
   <p>
    First Name:
    <asp:TextBox ID="FirstName" runat="server"></asp:TextBox></p>
   <p>
    Last Name:
    <asp:TextBox ID="LastName" runat="server"></asp:TextBox></p>
   <p>
    Address:<br />
    <asp:TextBox ID="Address" runat="server" TextMode="MultiLine"></asp:TextBox>
   </p>
   <asp:Button ID="AddRecord" runat="server" Text="Add" />
  </div>
 </form>
</body>
</html>

The WebHandler

Simply create a blank text file with the extension ashx, e.g. addrecord.ashx in the same folder as you ASP.NET page (although it is named addrecord, it could be used to modify existing records, get an associated photo etc.

<%@ WebHandler Language="C#" Class="AddRecord" %>

using System;
using System.Collections.Specialized;
using System.Web;

public class AddRecord : IHttpHandler
{

 public void ProcessRequest(HttpContext ctx)
 {
  ctx.Response.ContentType = "text/plain";
  if (ctx.Request.Headers["X-Requested-With"] == "XMLHttpRequest")
  {
   // get all form items
   NameValueCollection formItems = ctx.Request.Form;
   // loop through fields in the form
   foreach (string field in formItems)
   {
    ctx.Response.Write(field + " : " + formItems[field] + "\n");
   }
  }
  else
  {
   ctx.Response.Write("Access denied");
  }
 }

 public bool IsReusable
 {
  get
  {
   return false;
  }
 }

}

Comments

Post a Comment

Popular posts from this blog

Select box manipulation with jQuery

If you read the jQuery mailing list , you may be aware that I have updated my plugins for working with select boxes . Summary of changes: addOption replaces any options with the same value (so think of it as an add/replace options plugin selectOptions selected options in addition to what was already selected, but there is now an option for it not to do this There are two new methods: copyOptions which is for copying options between select boxes ajaxAddOption allows you to add options via AJAX (i.e. could be used for create options dynamically from a server script)
Read more

iTextSharp: Generating a Basic PDF file (ASP.NET/C#)

iTextSharp is free library for .NET that allows you to create PDF documents. It can be used to dynamically create PDF's which can be streamed to the user. As there is no HTML being sent to the user, a WebHandler (ashx file) is a more appropriate way to generate your PDF than an aspx page. Download itextsharp-3.0.10-dll.zip (latest version as of 08 Feb 2006) and save the dll in the archive to your websites bin directory. Here is a basic sample of creating a PDF (more complex samples may follow in future posts). BasicPDF.ashx <%@ WebHandler Language="C#" Class="MyNamespace.BasicPDF" %> using System; using System.IO; using System.Web; using iTextSharp.text; using iTextSharp.text.pdf; namespace MyNamespace { public class BasicPDF: IHttpHandler { public bool IsReusable { get { return true; } } /// <summary> /// Font used for any hyperlinks added to the PDF /// </summary> private Font LinkFont { get ...
Read more

Popup Window Countdown (JavaScript)

This code opens a new popup window that contains a timer that counts down, then closes the window when it reaches 0. Will not work if user has a popup blocker blocking the page. <html> <head> <title>Popup Timer</title> <script language="JavaScript" type="text/JavaScript"> // popup window var var popup; // At what number shall the countdown counter start? CounterStart = 10; // This function CustomAction() can be modified to do // whatever you want done every second. function CustomAction() { popup.document.timer.timeleft.value = CounterStart; } // end of function CustomAction() // end of JavaScript customization function Decrement() { CounterStart--; CustomAction(); if(CounterStart <= 0) { popup.close(); alert('Timer reached 0'); } else { setTimeout('Decrement()',1000); } } function StartTheCounter() { openPopup(120,100); setTimeout('Decrement()',1000); } f...
Read more