WooCommerce Subscriptions - Check if product already has an active subscriber

This custom made conditional function will return true if a subscription product is already actively used by a subscriber.

function has_an_active_subscriber( $product_id = null ){    // Empty array to store ALL existing Subscription PRODUCTS    $products_arr = array();    $products_subscr = get_posts( array(        'numberposts' => -1,        'post_status' => 'publish',        'post_type'   => array( 'product', 'product_variation' ),        'meta_key' => '_subscription_price',    ) );    foreach( $products_subscr as $prod_subs ) {        $products_arr[] = $prod_subs->ID;    }    // Testing if current product is a subscription product    if (in_array( $product_id, $products_arr) ){        // Declaring empties arrays        $subscribers_arr = array(); // ALL subscribers IDS        $active_subscriptions_arr = array(); // ALL actives subscriptions        $active_subscription_products_arr = array(); // ALL actif subscription products IDS IDS        $subscriber_subscriptions = array();        // Getting arrays of "active" IDS for subscribers, subscriptions orders and subscription products        $subscribers = get_users( array( 'role' => 'subscriber') );        foreach( $subscribers as $subscriber ) {            $subscriber_arr[] = $subscriber->ID;            $subscriptions = wcs_get_users_subscriptions($subscriber->ID);            foreach ($subscriptions as  $key => $subscription ){                $subscription_status = $subscription->post->post_status;                if ( $subscription_status == 'wc-active' ) { // active subscriptions only                    $subscription_id = $subscription->post->ID;                    $order_id = $subscription->order->post->ID; // order ID (corresponding to the subscription ID)                    $active_subscriptions_arr[] = $subscription->post->ID;                    $order_items = $subscription->order->get_items();                    // Getting all the products in the Order                    foreach ( $order_items as $item ) {                        // $item_id = $item[product_id];                        // Avoiding to add existing products in the array                         if( !in_array( $product_id, $active_subscription_products_arr ))                            $active_subscription_products_arr[] = $item[product_id];                    }                }            }        }    }    if (in_array( $product_id, $active_subscription_products_arr ) ) return true;    else return false;}

This code goes on function.php of your active child theme (or theme) or also on any plugin file.

I just have used here wcs_get_users_subscriptions() native subscription function, to get the subscriptions for a defined user ID, in my code.

USAGE (for a defined $product_id variable)

If ( has_an_active_subscriber( $product->id ) ) { // or $product_id    // This product is already used by an active subscriber    // DO SOMETHING HERE} else {    // This product is NOT used    // DO SOMETHING HERE}

You can also replace $product_id by a product ID here for example if the ID of the product is 124):

If ( has_an_active_subscriber( 124 ) )  //do something

You can use this conditional function particularly, on add-to-cart (subscription) templates (that you will have to copy from the subscription plugin templates folder to your active theme's woocommerce template folder…)

All code is tested and fully functional

References:

• Template Structure + Overriding Templates via a Theme
• WooCommerce Subscriptions developper docs