Wordpress change URL parameter on custom page

Question

I have a Wordpress site with a plugin in the backend which sets a $_GET parameter to my pages URL. Now I need to replace the value from this parameter with my custom value but this won't work:

My URL: http://localhost/wordpress/mein-konto/testpage/585/?conversationId=0

On the testpage/585 I've included a PHP file which get loaded on page load. In this file I have this function:

add_query_arg( 'conversationId', 1234, get_permalink() );

Now I'm expecting this URL here:

http://localhost/wordpress/mein-konto/testpage/585/?conversationId=1234

I'm not sure what I'm doing wrong.

Answer 1

Try this:

$conversationId = get_query_var( 'conversationId', '0' )

if ($conversationId === '0')
    wp_safe_redirect( add_query_arg( 'conversationId', 1234, get_permalink() ) )

It sounds like you are expecting add_query_arg to do the redirection, but it does not -- instead, it just returns a string that you can redirect to. So, just put the returned string into a call to wp_safe_redirect and you are good!

However, before redirecting to the same page you need to check whether the redirection is necessary -- otherwise you'll end up in an endless redirection loop (that your browser will detect and stop).