.htaccess redirect according to PHP parameters

Question

I'm trying to build some redirections with my .htaccess file to deal with some old forum url. I want the redirections to be made according to the PHP parameters (the topic ID).

For instance, something like

RewriteEngine On
RedirectPermanent /forum/viewtopic.php?t=123 /page1.html
RedirectPermanent /forum/viewtopic.php?t=345 /page7.html
RedirectPermanent /forum/viewtopic.php?t=89 /page3.html

The old and new URL are not related to each other (no PHP parameter has to be kept or something). I want to decide manually in my .htaccess file what to do for each topic ID.

But I can't manage to do that so easily. I tried many things, but nothing works.

Is this possible ? Any idea ?

Thanks a lot !

Edit : additional question : I want to add a global redirection of all the folder /forum to the root of the site ("/"). I guess I can place it after the others, so if no other rule is trigered, this one will be trigered.

I'm trying some things like

RewriteRule ^forum /? [L,R=301]

But everything I have tried so far redirects me to the "page1.html" (my first rule). Any idea why ? Thanks a lot !

Answer 1

You can't match against the query string using mod_alias's Redirect, RedirectMatch, etc. You need to use mod_rewrite and match against the %{QUERY_STRING} variable:

RewriteEngine On

RewriteCond %{QUERY_STRING} ^t=123$
RewriteRule ^forum/viewtopic\.php$ /page1.html? [L,R=301]

RewriteCond %{QUERY_STRING} ^t=345$
RewriteRule ^forum/viewtopic\.php$ /page7.html? [L,R=301]

RewriteCond %{QUERY_STRING} ^t=89$
RewriteRule ^forum/viewtopic\.php$ /page3.html? [L,R=301]

NOte that RewriteEngine is a mod_rewrite directive, not mod_alias. So it has no affect at all on the RedirectPermanent directives.