- -

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:

- -example.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:

- -

-example.com/product/1/
-example.com/product/2/
-example.com/product/3/
-example.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, CodeIgniter 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 -permits you to specify your own routing criteria. Routes can either be specified using wildcards or Regular Expressions

- - -

Wildcards

- -

A typical wildcard 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) 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"; -

A URL containing the word "journals" in the first segment will be remapped to the "blogs" class.

- -$route['blog/joe'] = "blogs/users/34"; -

A 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"; -

A URL with "product" as the first segment, and anything in the second will be remapped to the "catalog" class and the "product_lookup" method.

- -$route['product/(:num)'] = "catalog/product_lookup_by_id/$1"; -

A URL with "product" as the first segment, and a number in the second will be remapped to the "catalog" class and the "product_lookup_by_id" method passing in the match as a variable to the function.

- -

Important: Do not use leading/trailing slashes.

- -

Regular Expressions

- -

If you prefer you can use regular expressions to define your routing rules. Any valid regular expression is allowed, as are back-references.

- -

Note: If you use back-references you must use the dollar syntax rather than the double backslash syntax.

- -

A typical RegEx route might look something like this:

- -$route['products/([a-z]+)/(\d+)'] = "$1/id_$2"; - -

In the above example, a URI similar to products/shirts/123 would instead call the shirts controller class and the id_123 function.

- -

You can also mix and match wildcards with regular expressions.

- -

Reserved Routes

- -

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['404_override'] = ''; - -

This route indicates which controller class should be loaded if the requested controller is not found. It will override the default 404 -error page. It won't affect to the show_404() function, which will continue loading the default error_404.php file at application/errors/error_404.php.

- -

Important: The reserved routes must come before any wildcard or regular expression routes.