Add Post Slug Redirection with parameters

// NAV: Custom Redirect
function wpcoder_custom_redirect() {
    // Check if the current URL is the one you want to redirect
    if (is_single() && is_main_query() && get_post_field('post_name') === 'old-post-permalink') {
        // Define the new URL
        $new_url = home_url('/new-post-permalink/');

        // Get the query string from the current URL
        $query_string = $_SERVER['QUERY_STRING'];


        // Append the query string to the new URL
        if ($query_string) {
            $new_url .= '?' . $query_string;
        }

        // Perform the redirect
        wp_redirect($new_url, 301); // Use 301 for permanent redirect, or 302 for temporary redirect
        exit();
    }
}

// Hook the custom redirect function to the 'template_redirect' action
add_action('template_redirect', 'wpcoder_custom_redirect');

In this code:

• The is_single() function checks if the current page is a single post.
• The is_main_query() function ensures that it's the main query on the page.
• get_post_field('post_name') === 'old-post-permalink' checks if the post slug is 'old-post-permalink'.
• $_SERVER['QUERY_STRING'] to get the query string from the current URL and append it to the new URL.