public function get_field_value( $attendee_id ) {
		if ( ! $attendee_id ) {
			return null;
		}

		$value  = null;
		$values = get_post_meta( $attendee_id, Tribe__Tickets_Plus__Meta::META_KEY, true );

		if ( 'checkbox' === $this->type ) {
			foreach ( $this->extra['options'] as $label )  {
				$slug = $this->slug . '_' . sanitize_title( $label );
				if ( ! isset( $values[ $slug ] ) ) {
					continue;
				}

				// Save the Slug for checking which were saved
				$value[] = $slug;
			}

			if ( ! is_array( $value ) ) {
				$value = array();
			}
		} else {
			if ( isset( $values[ $this->slug ] ) ) {
				$value = $values[ $this->slug ];
			}
		}

		return $value;
	}