How to stop people going to particular URLs in Codeigniter

Say I have the url /product/view/1 which means I have the method in my product controller class:

function view($id)
{
    // Do s开发者_StackOverflow社区omething here
}

How do I get it to graciously fail if someone goes to /product/view?

Currently I'm getting two error messages, one saying Missing argument 1 for Budget::view() and one saying Undefined variable: id both of which I would expect, but obviously I'd rather provide my own one.

Two ways,

Option one: Give a default value for the $id variable by saying

function view($id = '')
{
     // Do something here and test if it's empty
}

This is what is traditionally done with optional parameters for functions in PHP

Option two: Rather than passing in the URI segment to the function as a parameter, you could alternatively get it using the URI helper (autoloaded by default)

function view()
{
     $id = (int) $this->uri->segment(3);
     // Do something here
}

Then you could test whether the id is set and do it from there

if your controller is product, and method is view

...
function view ( $id = null ) {
  // set graciously failing if $id = null to avoid error 
  // and make happend what you want
  ....
}
...

Don't know about any CodeIgniter specifics, but you can always redirect with .htaccess and mod_rewrite

RewriteEngine On
RewriteCond %{REQUEST_URI} ^/product/view$
RewriteRule ^(.*)$ http://www.example.com/your-error-document [R=301,NC,L]

function view($id = false)
{
    if ($id===false) {
        //show error
        show_error('your error');
        //or redirect
    }
    // Do something here
}