1-to-1, no ids, foriegn keys - I feel dumb

deniskrizanovic · **Joined:** Sun Mar 21, 2004 9:27 pm **Posts:** 5

Hi.

I'm trying to get a 1-to-1 mapping to work but I can't.

Basically, I've got an object that contains another object - unidirectional. Neither of these objects have ids. Incidently, they're JAXRPC generated.

I cannot for the life of me work out how to make this simple scenario happen. I've even gone so far, god forbid, to look at the code of ForeignGenerator!

My hbm file follows.

<hibernate-mapping>
<class name="LoadHP" table="LoadHotelPrices">
<id column="id" type="long">
<generator class="native"/>
</id>
<one-to-one name="rr" class="DKRoomRate"/>
</class>

<class name="DKRoomRate" table="RoomRates_Parent">
<id column="LoadHotelPricesType_id" type="long">
<generator class="foreign">
<param name="property">id</param>
</generator>
</id>
<property name="maxRoomMix" column="maxRoomMix"/>
</class>
</hibernate-mapping>

Do I need to have some association from DKRoomRate back to LoadHP?

regards,
dk-

gavin · **Posted:** Sun Mar 21, 2004 11:06 pm

<hibernate-mapping>
<class name="LoadHP" table="LoadHotelPrices">
<id column="id" type="long">
<generator class="native"/>
</id>
<one-to-one name="rr" class="DKRoomRate"/>
</class>

<class name="DKRoomRate" table="RoomRates_Parent">
<id column="LoadHotelPricesType_id" type="long">
<generator class="foreign">
<param name="property">lhp</param>
</generator>
</id>
<property name="maxRoomMix" column="maxRoomMix"/>
<one-to-one name="lhp" class="LoadHP"/>
</class>
</hibernate-mapping>

deniskrizanovic · **Joined:** Sun Mar 21, 2004 9:27 pm **Posts:** 5

hmm.. What would you say if I said, "it didn't work"?

I get this error.

net.sf.hibernate.PropertyNotFoundException: Could not find a getter for lhp in class DKRoomRate

gavin · **Posted:** Sun Mar 21, 2004 11:29 pm

Obviously, you need to add a new property to your class, to make the association bidirectional!

deniskrizanovic · **Joined:** Sun Mar 21, 2004 9:27 pm **Posts:** 5

But I don't want the association bi-directional. How do I make it work unidirectional?

The truth be told, I can't make it bi-directional, it's a generated class, out of Apache Axis.

regards,
dk-

gavin · **Posted:** Mon Mar 22, 2004 12:39 am

Actually, I should have said:

<one-to-one name="lhp" class="LoadHP" constrained="true"/>

of course.

Quote:

But I don't want the association bi-directional. How do I make it work unidirectional?

This is almost always a mistake, especially for the entity which owns the foreign key constraint. I think you need to rethink your object model here. Its just a bad design that will come back to bite you later on.

Your object model is important and should not be driven by whatever crap Apache Axis spits out :)

However, if you insist, then the solution is to not use the foreign id generator and manually ensure primary key equality by assigning ids to the DKRoomRate instances.

deniskrizanovic · **Joined:** Sun Mar 21, 2004 9:27 pm **Posts:** 5

hmm..

It's not working with the " constrained="true" " addition either.

Actually, whilst rereading your post, I come to another interpretation. Are you saying that the one-to-one mapping cannot do this automagically, and I -need- to set it up manually?

Quote:

This is almost always a mistake, especially for the entity which owns the foreign key constraint.

why? link (because I'm sure you've had to explain this before)?[/quote]

deniskrizanovic · **Joined:** Sun Mar 21, 2004 9:27 pm **Posts:** 5

> However, if you insist, then the solution is to
> not use the foreign id generator and manually
> ensure primary key equality by assigning ids to
> the DKRoomRate instances.

I just tried to do this, and it occured to me that I don't have any id members in my classes.

So, to reiterate,

- no ids,
- no bidirectionality
- cannot change code

But I still want to maintain FK consistency in a one-to-one manner. Any other ways of achieving this?

To give you bigger picture, I'm trying to use the axis generated classes as DTOs - save me thousands and thousands of lines of mundane code. In truth, I'm trying to use XMLBeans, but there is no 0-arg constructor, so I've had to fallback to axis.

gavin · **Posted:** Mon Mar 22, 2004 1:49 am

Quote:

I just tried to do this, and it occured to me that I don't have any id members in my classes

Code:

public interface Session extends Serializable {

   /**
    * Persist the given transient instance, using the given identifier.
    *
    * @param object a transient instance of a persistent class
    * @param id an unused valid identifier
    * @throws HibernateException
    */
   public void save(Object object, Serializable id) throws HibernateException;

Code:

Foo foo = new Foo();
Bar bar = new Bar();
foo.setBar(bar);

Serializable id = session.save(foo);
session.save(bar, id);

dannwebster · **Joined:** Wed Mar 24, 2004 7:40 pm **Posts:** 18

This is the part of the thread that I desparately want the answer to:

deniskrizanovic:

Quote:

But I don't want the association bi-directional. How do I make it work unidirectional?

gavin:

Quote:

This is almost always a mistake, especially for the entity which owns the foreign key constraint.

deniskrizanovic:

Quote:

why? link (because I'm sure you've had to explain this before)?

gavin <javadocs from the Session interface>

Is Gavin's last post in answer to this question or at least related to it? I am mystified by it. Can someone help me with this?

emmanuel · **Posted:** Mon Apr 05, 2004 3:57 am

dannwebster wrote:

Is Gavin's last post in answer to this question or at least related to it? I am mystified by it. Can someone help me with this?

Not related.
It is related to

Quote:

I just tried to do this, and it occured to me that I don't have any id members in my classes