mod_rewrite part of the query string

Question

I have a situation with opencart where I need to rewrite only the "route" leaving other query strings as it is. Example:

http://www.example.com/?route=module/ext/products&category_id=15&sort=newest

to

http://www.example.com/ext/products?category_id=15&sort=newest

how can I do that?

---

UPDATE: I have some constraints. This rewrite condition should only be applied to route=module/ecomapi/([^&]+). Not for other routes.

RewriteRule ^ecomapi/21/(products)/([^?]*)$ index.php?route=module/ecomapi/$1&product_id=$2 [L]
RewriteRule ^ecomapi/21/(login)/([^?]*)$ index.php?route=module/ecomapi/$1&email=$2 [L]
RewriteRule ^ecomapi/21/(users)/([^?]*)$ index.php?route=module/ecomapi/$1&id=$2 [L]
RewriteRule ^ecomapi/21/(products|navigation_drawer|banners|cart|login|d‌​evices|shops)?$ index.php?route=module/ecomapi/$1 [B,L,QSA]

Answer 1

Try the following near the top of your .htaccess file (or server config):

RewriteEngine On
RewriteCond %{QUERY_STRING} ^route=module/([^&]+)&?(.*)$
RewriteRule ^/?$ /%1?%2 [R,L]

This makes the following assumptions:

• An external redirect (302 - temporary). (Change the R flag to R=301 to make it permanent.)
• Only an initial request for the document root is considered.
• The route URL param always exists at the start of the query string.
• Everything after module/ in the route URL param value is extracted to form the URL-path in the substitution.
• There must be something after module/. But this "something" could be anything. (You should probably be as explicit as possible here in order to prevent matching against wholly invalid URL-paths.)
• The route URL parameter could be the only URL param.