public function __get( $key ) {
		wc_doing_it_wrong( $key, 'Coupon properties should not be accessed directly.', '3.0' );

		switch ( $key ) {
			case 'id' :
				$value = $this->get_id();
			break;
			case 'exists' :
				$value = $this->get_id() > 0;
			break;
			case 'coupon_custom_fields' :
				$legacy_custom_fields = array();
				$custom_fields = $this->get_id() ? $this->get_meta_data() : array();
				if ( ! empty( $custom_fields ) ) {
					foreach ( $custom_fields as  $cf_value ) {
						// legacy only supports 1 key
						$legacy_custom_fields[ $cf_value->key ][0] = $cf_value->value;
					}
				}
				$value = $legacy_custom_fields;
			break;
			case 'type' :
			case 'discount_type' :
				$value = $this->get_discount_type();
			break;
			case 'amount' :
			case 'coupon_amount' :
				$value = $this->get_amount();
			break;
			case 'code' :
				$value = $this->get_code();
			break;
			case 'individual_use' :
				$value = ( true === $this->get_individual_use() ) ? 'yes' : 'no';
			break;
			case 'product_ids' :
				$value = $this->get_product_ids();
			break;
			case 'exclude_product_ids' :
				$value = $this->get_excluded_product_ids();
			break;
			case 'usage_limit' :
				$value = $this->get_usage_limit();
			break;
			case 'usage_limit_per_user' :
				$value = $this->get_usage_limit_per_user();
			break;
			case 'limit_usage_to_x_items' :
				$value = $this->get_limit_usage_to_x_items();
			break;
			case 'usage_count' :
				$value = $this->get_usage_count();
			break;
			case 'expiry_date' :
				$value = ( $this->get_date_expires() ? $this->get_date_expires()->date( 'Y-m-d' ) : '' );
			break;
			case 'product_categories' :
				$value = $this->get_product_categories();
			break;
			case 'exclude_product_categories' :
				$value = $this->get_excluded_product_categories();
			break;
			case 'minimum_amount' :
				$value = $this->get_minimum_amount();
			break;
			case 'maximum_amount' :
				$value = $this->get_maximum_amount();
			break;
			case 'customer_email' :
				$value = $this->get_email_restrictions();
			break;
			default :
				$value = '';
			break;
		}

		return $value;
	}