public function trigger_meta_id( $user_id = null, $trigger_id = null, $meta_key = null, $recipe_log_id = null ) {

		// Set user ID
		if ( null === $user_id ) {
			$user_id = get_current_user_id();
		}

		// No user id is aviable.
		if ( 0 === $user_id ) {
			Automator()->error->add_error( 'get_trigger_meta_id', 'ERROR: You are trying to get trigger meta ID when a there is no logged in user.', $this );

			return null;
		}

		if ( null === $trigger_id || ! is_numeric( $trigger_id ) ) {
			Automator()->error->add_error( 'get_trigger_meta_id', 'ERROR: You are trying to get trigger meta ID without providing a trigger_id', $this );

			return null;
		}

		if ( null === $meta_key || ! is_string( $meta_key ) ) {
			Automator()->error->add_error( 'get_trigger_meta_id', 'ERROR: You are trying to get trigger meta ID without providing a meta_key', $this );

			return null;
		}

		global $wpdb;
		$table_name = $wpdb->prefix . 'uap_trigger_log_meta';
		$results    = $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $table_name WHERE user_id = %d AND meta_key LIKE %s AND automator_trigger_id = %d", $user_id, $meta_key, $trigger_id ) );

		if ( null !== $results ) {
			return (int) $results;
		}

		return $results;
	}