Rename page URL

Question

I have the following URL structure:

http://localhost/wordpress/gallery?id=331

id specifies the id of the post.

gallery is a normal page inside which I am accessing the id of the post and fetching the attachment images using WP_Query().

I want to replace the URL of this page to:

http://localhost/wordpress/topic/place/new-delhi/gallery?id=331

in which the parameters place and new-delhi may vary in multiple other options and topic is the keyword which remains the same.

I have tried using some unfruitful .htaccess file code.

Can anyone please help?

Answer 1

I have tried some add_rewrite_rule magic and query variables and it worked. Thanks for the help everyone.

If in case anyone want to refer the answer:

add_filter( 'query_vars', 'wpse26388_query_vars' );
function wpse26388_query_vars( $query_vars ){
    $query_vars[] = 'custom_gallery_id';
    return $query_vars;
}

add_rewrite_rule(
  'topic/([^/]+)/([^/]+)/gallery/([0-9]+)/?$',
  'index.php?pagename=gallery&custom_gallery_id=$matches[3]',
  'top' );

I was able to solve my problem with this.