Situation

I receive message from a 3rd party, and these messages are use to create or update database information.

Message and data to be updated can be de-serialize in object form, but are not exactly identical, so I need to use an object for mapping the properties of the incoming message object to the resulting entity.

The trick is that some of these properties must result in object retrieved from the database.

I have a set of DAO to handle all my database operations

Example (in Java code)

public class CarMessage {
    public String carType;
    public String carOwnerType;
    public String carOwnerId;
}

pubic class CarEntity {
    public String carType;
    public Person carOwner;
}

Question

Does the code doing the mapping can do the query in database ? Or do the database information retrieving should be done outside of the mapping code ?

In other words, should I do this :

public class CarMapper {

    private PersonDao personDao;

    public CarEntity mapMessageToEntity(CarMessage message) {
        CarEntity entity = new CarEntity();
        entity.carType = message.carType;
        entity.carOwner = personDao.retrievePersonFromDatabaseByTypeAndId(message.carOwnerId, message.carOwnerId);
        return entity;
    }   
}

public class MessageHandler {

    private CarMapper carMapper;
    private CarDao carDao;
    public void onMessage(CarMessage message) {
        CarEntity carEntity = carMapper.mapMessageToEntity(message);
        carDao.save(carEntity);
    }
}

or this :

public class CarMapper {


    public CarEntity mapMessageToEntity(CarMessage message) {
        CarEntity entity = new CarEntity();
        entity.carType = message.carType;

        return entity;
    }   
}

public class MessageHandler {

    private CarMapper carMapper;
    private CarDao carDao;
    private PersonDao personDao;

    public void onMessage(CarMessage message) {
        CarEntity carEntity = carMapper.mapMessageToEntity(message);
        carEntity.carOwner = personDao.retrievePersonFromDatabase(message.carOwnerId, message.carOwnerId);
        carDao.save(carEntity);
    }
}

Personally, I am more inclined in the second solution (all the DAO in the handler), as it make the error more manageable but I have some doubt and I would like to hear the pros and cons of the community.