SQL field type = array (Doctrine dbal)

Greetings to all!

Can someone explain me how to use Doctrine\DBAL\Types\Type?
In migration file I created column that have type array

$table->addColumn('filePrev', Type::TARRAY, ['notnull' => false,]);

In DB I succesfuly have column filePrev with comment (DC2Type:array)
Then, I spent a lot of time to figureout how to save $files = ['file_path1','file_path_2']; in that column and solution was:

use JsonSerializable;
use OCP\AppFramework\Db\Entity;
use Doctrine\DBAL\Types\Type;

class Task extends Entity implements JsonSerializable {

    protected $uid;
    protected $title;
    protected $description;
    protected $filePrev;
    protected $publishDate;

    public function __construct() {
        $this->addType('fileWork', Type::TARRAY);
    }

    public function jsonSerialize() {
        return [
            'id' => $this->id,
            'uid' => $this->uid,
            'title' => $this->title,
            'description' => $this->description,
            'filePrev' => $this->filePrev,
            'create_date' => $this->createDate,
        ];
    }
}

Finaly, half of all magic happened. Column fileWork have value a:2:{i:0;s:10:"file_path1";i:1;s:11:"file_path_2";}

Next I’m stuck (×_×)
When I making a query:

    public function findAll() {
        $qb = $this->db->getQueryBuilder();
        $qb->select('*')->from($this->getTableName());
        return $this->findEntities($qb);
    }

I’m geting serialized array:

Object
(
    [uid:protected] => oleg
    [title:protected] => Some title
    [description:protected] => 
    [filePrev:protected] => Array
        (
            [0] => a:2:{i:0;s:10:"file_path1";i:1;s:11:"file_path_2";}
        )
    [createDate:protected] => 2020-03-08 14:44:13
)

Question of life and deth what I shoud do to get filePrev unserialized like:

Object
(
    [uid:protected] => oleg
    [title:protected] => Some title
    [description:protected] => 
    [filePrev:protected] => Array
        (
            [0] => "file_path1",
            [1] => "file_path2",
        )
    [createDate:protected] => 2020-03-08 14:44:13
)