MVC - No Controller in the URI?

Let's pretend I'm trying to learn CI, and as my test project I am building a group-buying site.

What I'd like is to have a开发者_如何学C different page for each city, e.g.:

http://www.groupon.com/las-vegas/
http://www.groupon.com/orlando/

I'd also like to have different pages such as:

http://www.groupon.com/learn
http://www.groupon.com/contact-us

If I am building this in CI and following the MVC ideology, how would this work? I'm having difficulty seeing how to accomplish the desired URL's with the concept of:

http://www.domain.com/controller/view/segment_a/segment_b/etc...

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What I would do is create a custom 404 controller that acts as a catch-all for non-existent routes.

It would take the URI, possibly validate it, and re-route it to the (e.g.) "city" controller.

If the city controller can't find the city (whatever string was specified), then it needs to issue a proper 404. Otherwise, you're good to display your information for that city.

Also, once you create your custom 404 controller, you can send all 404 errors to it by specifying a route named '404_override'.

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That's where URI Routing comes in. But in your case you'll probably will have to be carefull defining your routes as the first and only part of your route is a variable part already.

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This really has nothing to do with MVC, and much more to do with good URL.

You're looking for URLs that are both (a) clear from the user's point of view and (b) that give hints to your application as to how it's meant to be handled.

What I'd do in this case is redesign your URLs slightly so that rather than:

http://www.groupon.com/las-vegas/
http://www.groupon.com/orlando/

You would have URLs that looks like this:

http://www.groupon.com/destinations/las-vegas/
http://www.groupon.com/destinations/orlando/

The bit at the beginning--/destinations/--can be used by your URL routing code to decide what controller should be dealing with it. If your routing code is URL-based, you might have an array like this:

$routes = array(
    '/destinations/' => 'on_destination_list',
    '/destinations/(.+)' => 'on_destination',
    '/(.*)' => 'on_page');

// Basic URI routing code based off of REQUEST_URI
foreach ($pattern => $func) {
    if (preg_match("`^$pattern$`", $_SERVER['REQUEST_URI'], $placeholders)) {
        array_shift($placeholders);
        call_user_func($func, $placeholders);
    }
}

Keep in mind that I wrote that routing code off the top of my head and it may not be absolutely correct. It should give you the gist of what you need to do.

Doing things this way has the added benefit that if somebody goes to http://www.groupon.com/destinations/, you'll have the opportunity to show a list of destinations.