Emran Hasan's Blog

Greetings to all the readers of my blog.

Many of you have been writing to me in the last couple days when I took the site down. The main objective was to add the new theme and push a few code updates of the existing libraries. I really appreciate your concern and would like to reassure you that the site is up and will be up as usual Now, besides the slightly customized theme from Elegant Themes, I have put a few code updates. They are detailed below:

Extended Model for CodeIgniter

The original version of the Extended Model for CodeIgniter has been serving many people well. Although most users loved the nifty functions of the Model, many (including me) didn’t like the hacking of CI core to get this functionality. With the release of CodeIgniter 1.7, we can avoid that as we can now overload the Model class of CI like the other libraries. Follow this instruction:

1. Download the updated version from here
2. Put it in your application/libraries folder
3. In your model files, use it this way: class Product extends MY_Model
4. Everything else is same just like the original one

HTTP Class

There is not much update in this class except for a few bug fixes (thanks to you guys). Also, I have included a license file in the package as many of you have asked. It’s released under the MIT license. The original post is here for reference.

Download the update from here and the API reference is here.

Cross-domain AJAX calls using PHP

A minor bug fix in the code. Thanks to a few of you who pointed them out. Original post is here. Download the update from here.

I have accelerated plans for the blog in 2009 so stay tuned for some worthy posts in this month. And do write to me if you feel you have any questions/ideas/suggestions.

Cheers!

AJAX has become the core component of many web applications around us. And its fairly easy to handle AJAX now a days, with the help of various javascript libraries (ex: jQuery, Prototype, Mootools, YUI, etc). But there is one security issue that web browsers impose in doing AJAX calls – they don’t let you do AJAX calls in web servers different than yours. That means, if your script is in www.mydomain.com and you’re trying to do AJAX call to www.anotherdomain.com/get.php, then the browser will through error like: “Error: uncaught exception: Permission denied to call method XMLHttpRequest.open”.

Now, there are a number of solutions to this problem. Instead of explaining them all to you, lemme provide you the simplest one: using a PHP transport file. If you already know the thing and just need the script, download from here.

Others, let’s see an example implementation first.

Example use

   1: xmlHttp.onreadystatechange=function()

   2: {

   3:     if(xmlHttp.readyState==4)

   4:     {

   5:         alert(xmlHttp.responseText);

   6:     }

   7: }

   8:  

   9: xmlHttp.open("GET", 'http://myserver.com/transport.php?action=' + 

  10:                     urlencode('different-server.com/return_call.php') +

  11:                     '&method=get&data1=101&data2=pass', true );

  12:  

  13: xmlHttp.send(null);

Now, lets see how it works:

1. The script makes an AJAX call to the myserver.com/transport.php with a few parameters:
   • action = the target URL you need to fetch, from a different domain
   • method = the HTTP method (post/get)
   • data1, data2 = sample parameters for using as either query-string or POST fields
2. When the request is received by transport.php, it uses cURL to make a call to the page mentioned in action.
3. Based on the method, it either makes a GET request or a POST request. In both cases, it sends the extra parameters that are sent.
4. After the response is received, transport.php echoes it. So, you have what you need!

Download

transport.php Cross-Domain AJAX call transporter. Downloaded: times

Comments and suggestions are most welcomed