how to best design the mapping for the following problem:

I've got 2 tables:

TRAINING_SESSION
---------------------------
ID1
INFO

and

STATE
---------------------------
ID2
NAME


I need to store the amount of people getting a training per State.
I've got an association table (say EFFECTIVES) that's reference both table and that store the amount of people participating to the training per state:

EFFECTIVES
---------------------------
ID1
ID2
QUANTITY

I've already successfully mapped such index tables thnks to <set> attributes. It works great and seemlessly.
But since i've an info here on the index (QUANTITY) I'm wondering how to best implement that.
I think the best for me would be to have a Collection of (STATE_NAME, QUANTITY) object.
Is there anyway to define an object structure composed of various field from various table and associtae it to a mapping?
<bag> or <set> could probably help me here but I'm not familiar with those.

Any help would be welcome!

The easiest thing would be to use <composite-element> inside of the collection mapping. Take a look here http://www.hibernate.org/hib_docs/reference/html/collections.html#collections-s1-5

OK, I found out some something that seems to work but it is quite far fetched compare to a simple set (just to add a property field)

I still got some weird behavior with it:

I added this to my TRAINING mapping:


Then I had to create a mapping for the STATE_EFFECTIVE_INDEX table (I wish I could avoid it)


It seems to work (I only been testing loading though), but when I get my stateEffcetive list the quantity field is filled up but not the 2 other keys (composite-id).

Is there any simpler way to achieve this or is it the right way?

thanks lot for answering my newbie questions....

I tried with <bag> instead of list, removing the index, but still get null values for the identifiers. I would ideally like to get the STATE name and not even the stateCode...

I did an attempt to add a

<many-to-one name="stateCode" column="STATE_EFFECTIVE_CODE_FK" class="State" not-null=true/>

in order to actually get a State object.
As expected I received the following error: "Repeated column in mapping..."
so had to add insert="false" update="false" and am still unable to get anything else than the QUANTITY...

Help!

Use something like this:


Or map the thing as a map, with the related class as an index, and the quantity as value:

thanks a lot for responding, I was really looking forward some help here.

So I tried the first solution, but the other way around since I need the State effective in the Training class.

It looks like this:



But I got a net.sf.hibernate.PropertyAccessException when trying to load a Training object:


It's probably because of the <composite-id>. Is it possible to get rid of it since I don't want to make explicit use of this mapping?

I'm gonna try to work on the second option too.

You do not need to map StateTraining if you use it as composite-element.

Ok, I 'm really glad it finally works. I had to regenerate the class from the mapping of my Training class.

What are the pros & cons against the second option?

Is it possible to get the STATE_NAME as a property into the <composit-element> so that the developper doesn't even have to know about the State object, but just get the info it needs, i-e collection of participantQuantity, StateName pairs ???