Hi folks,

I read the book Hibernate in action .. and in chapter 8, when they are working a real bid system example.. and refactoring..

they finish up with some data access object (DAO) which internally use Hibernate to get stuff from the underlying persistence store which is fine with me.

Where I start to question the design is when they have a method in the itemDAO class that returns the minimum and maximum bid for a given item (that is passed as a parameter)

here is the code:
BigDecimal currentMaxAmount = itemDAO.getMaxBidAmount(itemId);
BigDecimal currentMinAmount = itemDAO.getMinBidAmount(itemId);
Item item = itemDAO.getItemById(itemId);
User user = userDAO.getUserById(userId)
newBid = item.placeBid(user, newAmount,
currentMaxAmount, currentMinAmount);


I would have thought that the item class which has a placeBid() method should be responsible for knowing its own min / max bid. The way it is right now, it's up to the calling method to provide it to the placeBid.

Is there something I misunderstood here?

Thanks

Also,


as long as I have an object in the persistance store, I can use the DAO to get it.. but what's the best way to persist a newly created object?

I mean I could Item item = itemDAO.getItem(id); if I have an item in the db..

but if I do

Item item = new Item();
// set item's properties

then using the architecture describe in the book, in the filter, the session would be close and therefor all persistance object would be saved. but since my newly created item is in transient state, it needs to be attached in some ways to the session. How should it be done according to the Hibernate in action book?

Thanks again.

Any thoughts on any of the above?

Thanks

Hi martbl,
you could write a abstract BaseDAO class with owns a generic save(Object objectToSave) method. In this case just inherit each DAO from your base dao an associate your transient objects by calling the save method.


simon

That's what I did.. but I thought there would be a more elegant way :)

Thanks!