How to change URL argument from arg-1 to arg_1 before apache processes it? use .htaccess? - apache

Question

I have a CMS that takes url arguments to return a list of results with this structure:
website.com/argument_1/argument_2.
In order for the site to return the results the args have to have underscores.
However, the code that is generated for the url structure is
website.com/argument-1/argument-2. I need to keep this url structure, but, when someone clicks the link, I need it passed to PHP via apache with the underscores.
I hope that makes sense. Is this done with .htaccess and rewrite rules? I have never written any thing like that before, so any help is appreciated. Thanks

Answer 1

You should definitely do this in PHP. Here is a solution that will work, but requires one pass through RewriteRule for each dash in the URL, so I don't recommend it. But regardless:
RewriteEngine On
RewriteRule ^(.*)-(.*)$ $1_$2 [QSA]
To clarify what will happen here, if the request is for http://www.example.com/argument-1/argument-2/argument-3, the RewriteRule will be run multiple times because it can only replace a single dash per pass. So the URL will be transformed something like this:
Pass 1: http://www.example.com/argument-1/argument-2/argument_3
Pass 2: http://www.example.com/argument-1/argument_2/argument_3
Pass 3: http://www.example.com/argument_1/argument_2/argument_3
As for the $1 and $2, these refer back to the parenthesized components from the regular expression. The regular expression, ^(.*)-(.*)$, breaks down like this:
^ - Match the beginning of the URI
(.*) - Match (and capture) any number of characters, this will be $1 in the replacement
- - Match a dash
(.*) - Match (and capture) any number of characters, this will be $2 in the replacement
$ - Match the end of the URI
So the first pass through, $1 will be /argument-1/argument-2/argument and $2 will be 3. The replacement then puts an underscore between the 2 of them and creates a new URI:
/argument-1/argument-2/argument_3
Then it runs again because the regular expression still matches the new URI (because it has a - in it) and $1 is /argument-1/argument and $2 is 2/argument_3. The replacement then puts an underscore between the 2 of them and creates a new URI:
/argument-1/argument_2/argument_3
Then it runs again because the regular expression still matches the new URI (because it has a - in it) and $1 is /argument and $2 is 1/argument_2/argument_3. The replacement then puts an underscore between the 2 of them and creates a new URI:
/argument_1/argument_2/argument_3
Then Apache continues with this URI since the regular expression no longer matches (because there are no more dashes).