Conditional custom redirect

Question

I want to achieve the following:

• On a post or a page, I can define an optional custom redirect URL (possibly as an Advanced Custom Field)
• If I view this post/page with a specific added URL parameter (like "?redirect=true", send a redirect to the defined custom URL, otherwise do not redirect.

My naive approach would be to add this as a javascript to the post/page template.

Is there a better option? Or a plugin I could (ab)use for that purpose?

Answer 1

It should not be tough. As you suggested you can use ACF to add a custom field in post/page and then use the template_redirect action hook to check if the current page's custom field is a valid URL as well as $_GET['redirect'] is true, wp_redirect to that URL.

function my_page_template_redirect()
{
    if( is_url(GET_ACF_FIELD_VALUE( 'CUSTOM_FIELD' )) && !empty($_GET['redirect']) && $_GET['redirect'] == 'true)
    {
        wp_redirect( GET_ACF_FIELD_VALUE( 'CUSTOM_FIELD' ) );
        exit();
    }
}
add_action( 'template_redirect', 'my_page_template_redirect' );