URI Routing
Typically there is a one-to-one relationship between a URL string and its corresponding controller class/method. The segments in a URI normally follow this pattern:
www.your-site.com/class/function/id/
In some instances, however, you may want to remap this relationship so that a different class/function can be called instead of the one corresponding to the URL.
For example, lets say you want your URLs to have this prototype:
www.your-site.com/product/1/
www.your-site.com/product/2/
www.your-site.com/product/3/
www.your-site.com/product/4/
Normally the second segment of the URL is reserved for the function name, but in the example above, it instead has a product ID. To overcome this, Code Igniter allows you to remap the URI handler.
Setting your own routing rules
Routing rules are defined in your application/config/routes.php file. In it you'll see an array called $route, that you can use to specify your own routing criteria. A typical route might look something like this:
$route['product/:num'] = "catalog/product_lookup";
In a route, the array key contains the URI to be matched, while the array value contains the destination it should be re-routed to. In the above example, if the literal word "product" is found in the first segment of the URL, and a number is found in the second segment, the "catalog" class and the "product_lookup" method are instead used.
You can match literal values or you can use two wildcard types:
:num
:any
:num will match a segment containing only numbers.
:any will match a segment containing any character.
Note: Routes will run in the order they are defined. Higher routes will always take precedence over lower ones.
Examples
Here are a few routing examples:
$route['journals'] = "blogs";
Any URL containing the word "journals" in the first segment will be remapped to the "blogs" class.
$route['blog/joe'] = "blogs/users/34";
Any URL containing the segments blog/joe will be remapped to the "blogs" class and the "users" method. The ID will be set to "34".
$route['product/:any'] = "catalog/product_lookup";
Any URL with "product" as the first segment, and anything in the second will be remapped to the "catalog" class and the "product_lookup" method.
Important: Do not use leading/trailing slashes.
Reserved Route
There are two reserved routes:
$route['default_controller'] = 'welcome';
This route indicates which controller class should be loaded if the URI contains no data, which will be the case when people load your root URL. In the above example, the "welcome" class would be loaded. You are encouraged to always have a default route otherwise a 404 page will appear by default.
$route['scaffolding_trigger'] = 'scaffolding';
This route lets you set a secret word, which when present in the URL, triggers the scaffolding feature. Please read the Scaffolding page for details.