Laravel Eloquent：将集合保存到数据库并从数据库中检索为集合

I am saving a collection to table column.

$collec = Modal::find(2)->toArray();

$someOther = new NewModal;
$someOther->template = json_encode($collec);
$someOther->save();

But when i retrieve the collection from the column with json_decode(), It gives me read only object which i can't work with.

Any way around it ?