mod_rewrite query strings returning 404 - php

Question

I have a custom URL like this:
website.com/show/?id=9999&n=page-name
I'm trying to come up with a rewrite rule to convert it to:
website.com/show/9999/page-name/
Note that this is a WordPress site and /show/ is WP page name.
Here's the rules I'm using in .htaccess:
<IfModule mod_rewrite.c>
Options -MultiViews
RewriteEngine On
RewriteBase /
RewriteRule ^show/(.*)$ /show/?id=$1 [R=301,NC,QSA]
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
This is working; it rewrites website.com/show/?id=9999 to website.com/show/9999/.
Then I modified the rule for the second query string:
RewriteRule ^show/(.*)/(.*)$ /show/?id=$1&n=$2 [R=301,NC,QSA]
But now website.com/show/9999/page-name/ returns a 404 error. It works if I go to: website.com/show/9999/?n=page-name.
What am I doing wrong?
Update
The 404 problem is now solved.
However, now I need to redirect the old query string URL:
website.com/show/?id=9999&n=page-name
to the new SEO friendly URL:
website.com/show/9999/page-name
How do I setup that redirect?

Answer 1

Try this:
Options +FollowSymLinks
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteRule ^show/(\d+)/?([^/]*)/?$ /show/?id=$1&n=$2 [L,NC,QSA]
# Wordpress defaults:
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
## Results
# show/9999 => show/?id=9999&n=
# show/9999/ => show/?id=9999&n=
# show/9999/page-name => show/?id=9999&n=page-name
# show/9999/page-name/ => show/?id=9999&n=page-name
As you see, when page-name is not available, there will be an empty n query string parameter. In your PHP script, instead of checking for the parameter presence using isset(), try using empty().
One last note; The above rules do not redirect the request, it maps the request under the hood, so that the URL stays clean. If you need a redirect, just add a R flag.
404
Even if you remove your custom rewrite rules, you'll get a 404 from WordPress. That's because, as you said, the rewrite target (/show) is a WordPress page and ultimately get mapped to the index.php file. Then, WordPress checks its database to see if it can find a page with that path or throws a 404 if it can't. Obviously, the latter is your case.
Update
Regarding your recent update; To redirect the old URL to the new one, you need some rewrite rules along the lines of:
Options +FollowSymLinks
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteCond %{QUERY_STRING} ^id=(\d+)(&n=)?(.*)$
RewriteRule ^show/?$ /show/%1/%3 [R=301,QSD,L]
# Wordpress default rules:
# ...
</IfModule>
## Results
# show?id=9999 => show/9999
# show?id=9999&n=page-name => show/9999/page-name
# show/?id=9999&n=page-name => show/9999/page-name
Don't use [R=301] until you're 100% sure that everything's working fine, as it's aggressively get cached by the browser.

Answer 2

I think I figured it out... almost.
#sepehr is correct that WordPress is checking, not finding the page, and throwing a 404. So I needed to use WordPress' own rewrite engine to define the rewrite rules so it recognizes what I'm doing.
So I added this to my WordPress theme's functions.php file:
add_action( 'init', 'init_custom_rewrite' );
function init_custom_rewrite() {
add_rewrite_rule(
'^show/([^/]*)/([^/]*)/?',
'index.php?page_id=2382&id=$matches[1]&n=$matches[2]',
'top'
);
}
add_filter('query_vars', 'my_query_vars', 10, 1);
function my_query_vars($vars) {
$vars[] = 'id';
$vars[] = 'n';
return $vars;
}
Now the URL website.com/show/9999/page-name works correctly, not throwing a 404.
However, now I need to redirect the old query string URL to this new one. See my updated question.
Update
Here's the rewrite rule to redirect the old query string URLs to the new SEO friendly URLs:
RewriteCond %{QUERY_STRING} ^id=([^/]*)&n=([^/]*)$
RewriteRule ^show/?$ /show\/%1\/%2\/? [R=301,L]

Answer 3

Please check below rule in to your .htaccess.
RewriteRule ^show/(.+)/(.+)$ show/?id=$1&n=$2 [L,QSA]