izzum\statemachine\persistence\PDO::isPersisted PHP Method

    public function isPersisted(Identifier $identifier)
    {
        $connection = $this->getConnection();
        $prefix = $this->getPrefix();
        try {
            $query = 'SELECT entity_id FROM ' . $prefix . 'statemachine_entities WHERE ' . 'machine = :machine AND entity_id = :entity_id';
            $statement = $connection->prepare($query);
            $machine = $identifier->getMachine();
            $entity_id = $identifier->getEntityId();
            $statement->bindParam(":machine", $machine);
            $statement->bindParam(":entity_id", $entity_id);
            $result = $statement->execute();
            if ($result === false) {
                throw new Exception($this->getErrorInfo($statement));
            }
            $row = $statement->fetch();
            if ($row === false) {
                return false;
            }
            return $row['entity_id'] == $identifier->getEntityId();
        } catch (\Exception $e) {
            throw new Exception(sprintf('query for getting persistence info failed: [%s]', $e->getMessage()), Exception::PERSISTENCE_LAYER_EXCEPTION);
        }
    }