Getting Started With CodeIgniter URL Routing

In this tutorial, I will try to give an overview on codeigniter url routing. I will also describe the basic implementation technique with necessary code examples where needed. I am assuming you already know about PHP and worked/has knowledge in codeigniter basics. You should also be familiar with how model-view-controller works and how codeigniter url structure works.

What is CodeIgniter URL Routing, And Why Is It Required?

We all want to show our web page in a more convenient way so that it makes more sense to visitors(and to search engines, of course). For example, one should understand in brief what content a page contains just by checking out the URL in the browser address bar. If we keep this as it is in a way that can be understood by server scripts(PHP, Asp.NET, etc), like as follows, it shouldn’t fulfill our goal much:

http://yourdomain.com?p=1
http://yourdomain.com?p=2
http://yourdomain.com?w=30
http://yourdomain.com?z=234
//etc......
Code language: JavaScript (javascript)

From the above links, there is no way to understand what those pages are about. Now, what if it was something like the following:

https://codesamplez.com/database/codeigniter-activerecord
<blockquote class="wp-embedded-content" data-secret="ww8oEBqEXL"><a href="https://codesamplez.com/programming/regular-expressions-in-php">Beginners Guide To Use Regular Expression In PHP</a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="“Beginners Guide To Use Regular Expression In PHP” — CODESAMPLEZ.COM" src="https://codesamplez.com/programming/regular-expressions-in-php/embed#?secret=GoOJWS0mSL#?secret=ww8oEBqEXL" data-secret="ww8oEBqEXL" width="500" height="282" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe>
Code language: JavaScript (javascript)

These are much more meaningful, we can have a brief idea from just seeing the URL. Also, search engines give more value than earlier URLs, which is why they are known as ‘search engine friendly URLs’. So, just as companies like Victorious recommend, whatever reason you choose, it’s always better to use SEO-friendly URLs. Ok, now, we have decided to make our site more SE/visitor-friendly and want to use these URLs. Now, how should we develop our application to map this url to the original request handler scripts?

Url Rewriting/Routing actually is the technique which converts this seo friendly urls to a format that server code can understand easily/drives a request to their corresponding request handler scripts.

Url Rewriting/Routing Techniques

HTTP Server (IIS,Apache) provides some ways/programming syntax with which URL Rewriting is done. In the Apache web server, the access programming technique has some ways to do this routing. However, “htaccess “isn’t very easy to consume, especially for beginners; even Apache mod_rewrite documentation; there, it is mentioned that “mod_rewrite’s major drawback is that it is not easy to understand and use for the beginner.” Also, to understand this a little better, you will need to understand regular expression basics as well, as most of the “htacess” rules are written in regular expression format.

Another way is to process the URL from the server script itself. We can get primary help from the server to forward all requests to a specific server script, where, with our programming skills, we can parse the URLs and process them accordingly. However, that one will not be a very easy task as well. However, on cms and frameworks, there is some integrated functionality to do that work. Codeigniter also provides a very good, convenient and easy way with the rich customizable facility to implement this routing on our application.

Routing URLs with Codeigniter:

In this tutorial, we will first send all requests to a single controller method on our Codeigniter application, where most of the requests should go, and will route other requests to their specific controller methods. Just make sure your server is Apache and has mode_rewrite mode installed and enabled, then you can use the following code snippet to make it easier to rewrite all server requests by mapping them to a single controller method(you won’t have to learn htaccess for this):

<IfModule mod_rewrite.c>
 
    RewriteEngine On
    RewriteBase /
 
    # Disable rewrite for valid directory/files
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d 
 
    #map all request urls to a specific controller method
    RewriteRule ^(.*)$ index.php?/{controller}/{method}/$1 [L]
</IfModule>Code language: PHP (php)

Now, all requests are going to be sent to your specific controller’s specific method as a function parameter.

Now, we will want to separate some requests and redirect them to their own corresponding controller/method. To make this happen, please go to the file ‘{root}/system/application/config/routes.php’ and open it. At the bottom of the pages, you will have to add the routing rules with which you want the requests to be routed. Here are a few types of rule samples for routing:

//For pages those have a static name
$route['{default_controller}/{default_method}/about.html'] = "{original_controller}/{original_method}";
 
//rule to rout request with number values
$route['{default_controller}/{default_method}/(:num)'] = "{original_controller}/{original_method}/$1";
 
//rule to rout request with regular expression values
$route['{default_controller}/{default_method}/([a-z]+)-{delimiter}'] = "{original_controller}/{original_method}/$1";
Code language: PHP (php)

Dash-based URLs To Underscore-Based Function:

Well, there is a common problem, that beginners fell most often in working with codeigniter url routing. That is, a controller function name can contain an underscore but not a ‘dash’ character, which is very common use in nowadays web applications. So, a requirement of mapping those ‘dash’ based URL names into ‘underscore’ based controller function names comes in the way naturally. To get a robust solution for this, add a new class in your ‘application/core’ directory as follows:

<?php (defined('BASEPATH')) OR exit('No direct script access allowed');
 
class MY_Router extends CI_Router
{
    function _set_request ($seg = array())
    {
        // The str_replace() below goes through all our segments
        // and replaces the hyphens with underscores making it
        // possible to use hyphens in controllers, folder names and
        // function names
        parent::_set_request(str_replace('-', '_', $seg));
    }
}
Code language: HTML, XML (xml)

You won’t have to do anything else additionally. It will be automatically loaded by the codeigniter and will be in action for any URLs.

References

As you are a ci developer, you already know that, there is a very rich, easy to understand documentation on Codeigniter’s functionality, it also has well described documentation on codeigniter url routing as I mentioned above. Also, if your need isn’t fulfilled with any of them(my article and Codeigniter documentation), please mention it here so that I can come to know, and I will try my best to find a solution. Happy coding 🙂