New snippet to restrict purchases for the same active subscription again

[mihaijoldis]

Was requested by a customer that if the user has an active subscription for Download X he should not be allowed to buy it again.
Code that seems to work:

function pw_edd_recurring_limit_one_subscription( $valid_data, $post_data ) {

	if( ! is_user_logged_in() ) {
		return;
	}

	$subscriber = new EDD_Recurring_Subscriber( get_current_user_id(), true );
	$cart_contents = edd_get_cart_contents();

	foreach( $cart_contents as $item ) {
		if( $subscriber->has_active_product_subscription( $item['id'] ) ) {
			edd_set_error( 'duplicate_item', 'You have already purchased this item so may not purchase it again' );
		}
	}

}
add_action( 'edd_checkout_error_checks', 'pw_edd_recurring_limit_one_subscription', 10, 2 );