Writing web applications with CodeIgniter – Part 3

We built a simple to-do list application last week by implementing the CI basics we learnt in first part of this tutorial. Today, let’s go over some of the things that will allow you to customise and extend the CI framework for your specific needs.

Changing the default URL routing

As we have already seen, CI parses the URLs in the following format:

example.com/className/functionName/variable1/variable2

While this suits most of the times, sometimes we might want to tweak CI to handle things different. With a reference to the blog example we saw in the first part, say, we want to display the entries of a blog by accessing a URL along the lines of "example.com/post/postID". Here, we actually want the "postID" to be parsed as a variable rather than a function name.

CI allows us to make such tweaks by allowing us to write our own routing rules. These rules are defined in application/config/routes.php file in an associative array called $route . The key of the associative array will define the URI to be matched, and its corresponding value will be the destination URI to which the request to be routed to. Apart from providing two…

Writing web applications with CodeIgniter – Part 2

Last week, we covered the basic structure of a CodeIgniter application. Let’s now jump right into developing a simple todo list application using CodeIgniter. We will be keeping the actual functionality of the application itself simple here, as the goal here is to give a good overview on what it takes to build a CI application from scratch.

Okay, the first thing you have to do is to download and extract the latest build of CodeIgniter. Next, download the controllers, models and views that I have used in this sample todo list application. You should refer to these files as you read the tutorial. Here is the demo of the sample application (use “demo” as username and password).

Directory structure

All the files related to our application will be placed in the "system/application" folder:

As you can see, we have to place our controllers, views and models in their correspondng /controllers, /views and /models directories. Initially, we will have a sample controller (Welcome) in the /controllers directory, and its corresponding Welcome view in the /views directory. The model directory will be empty.

The /config directory consists of various files which will help us…