mod_rewrite complexity problem

Question

I have a need to mod-rewrite my domain based off of subdomains...there are two scenarios in which i would need to do this:

1. my site is located in different cities...so losangeles.example.com should localized to los angeles, etc...essentially rewritten to www.example.com/?loc=losangeles

2. i want to allow users to create username.example.com to pass their profiles to friends with ease...essentially rewritten to www.example.com/user.php?id=username

As my site scales, I plan on having over 300 locations, and several thousand users...which means that hand coding each rewrite rule would be a little tedious.

How can I tell mod-rewrite to decipher between a location subdomain and a username subdomain?

Answer 1

I think fundamentally you need to rethink that strategy as mixing your namespaces is going to cause a lot of headaches in the long term. Consider what happens if you have missed out a city name, such as alexandra.example.com but a user has registered that username? Also, you are going to end up with having to do things like checking whether a city exists at the point that a username is trying to be created.

If you really do want to stick with this, one possibility is simply to send the requests to a single point which then does the lookup against your two databases and then internally sets a variable of either $city or $user .

Once you have set up your DNS wildcarding, in Apache set:

ServerAlias *.example.com

and then the rest of your virtualHost as normal.

Then in the application just check against $_SERVER['SERVER_NAME'], e.g.

$server_name = addslashes($_SERVER['SERVER_NAME']);    
$query = "select * from instances where '{$server_name}' regexp replace(concat(server, '$'),'.','\.') limit 1";

but then you're actually going to have to have two queries and additional logic to pull apart the two namespaces or handle clash situations.

I would use a namespace like

<cityname>.example.com/user/<username>

which will avoid the problems, and also mean that you can customise what is visible on the user's homepage depending on which city you've entered, if that is desirable.