how to set status header to 200 in wordpress theme / plugin

I am currently working on a WordPress auction plugin. The plugin stores item in a separate table. I have successfully created the plugin and is working as expected (in the admin area).

Now I am trying to build a theme that will utilise the plugin. I need to display all the auction items in the front-end of the site. When a user visits url www.somesite.com/auctions/2, I want to display details of auction with id 2.

I have successfully written a .htaccess redirect that will get the id, so I can use the id to find the auction in the table and display its detail. But the problem not is that WordPress displays 404 page if I visit that url.

This is what I have tried.

.hatccess

RewriteRule ^(auction)/(.*)$ ?action=$1&id=$2 [L]

So now if someone visits /auction/1, var_dump(id) will get me 1. I have a Auction class for which I intend to get the respective auction by doing $auction->get(id) in my theme.

So far everything works fine, apart from the 404 page I get when I visit the url. I have tried following to get rid of the 404 page if someone visits the url.

// code below this point doesnt work as intended.

public function resolveURL(){
    global $wp_query;

    $action = $_GET['action'];
    $id = $_GET['id'];

    if($action == 'auction' && !empty($id)){

        status_header(200);
        $wp_query->is_page = $wp_query->is_singular = true;
        $wp_query->is_404  = false;
  }
}

And in my theme base.php i call:

  global $wppa; // plugin object
  $wppa->resolveURL();

I want to not get the 404 page when I call the function and the url is /auction/someid. Any help will be appreciated.

Thanks in advance.