Hibernate version:3.1

I want to map a class A with a class B that have a composite id. The scenario is like that:

--- CLASS A ---------
<class name="A" table="A_TABLE">
<id name="id" column="ID" type="integer">
<generator class="assigned"/>
</id>
.....
</class>

--- CLASS B ---------

<class name="B" table="B_TABLE">
<composite-id name="pk" class="B_PK">
<key-property name="ID_A" column="KEY_1" type="int" />
<key-property name="seq_B" column="KEY_"" type="int" />
</composite-id>

.....
</class>

In A_TABLE I have columns for ID_A (obvious) and sec_B, but How I say that map the columns in A to get the B instance?

I try using one-to-one and many-to-one, but I had not luck.

I try using a PK object too, but again, how say map the columns in A to get the right instance of B.

Regards,
Ernesto.

I had something like this to do on our product database with things like features, specifications, addons, and warranties, and a single Category.

In my Product class, I have lists of features, specifications, addons, warranties, and a single Category instance.

I explicitly define even the more primitive types, but I hope it's readable and useful.

I did the following with the addons:

In the Product.hbm.xml mapping I included this bit:

<bag name="addons" table="addon">
<key column="product_id" />
<many-to-many column="addon_product_id" class="com.mycompany.business.product.Product" />
</bag>

For its own Addon.hbm.xml mapping I do this:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping default-lazy="false">

<class name="com.mycompany.business.product.Addon" table="addon">

<composite-id unsaved-value="none">
<key-many-to-one class="com.mycompany.business.product.Product" name="productId" column="product_id"/>
<key-many-to-one class="com.mycompany.business.product.Product" name="addonProductId" column="addon_product_id"/>
</composite-id>
</class>

</hibernate-mapping>

If it's only a single value, you might try something like I used for a product's category:


In the Product.hbm.xml mapping:

<many-to-one name="category" column="category_id" class="com.mycompany.business.category.Category" />

In the Category.hbm.xml mapping:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping default-lazy="false">

<class name="com.mycompany.business.category.Category" table="category">
<id name="id" column="id" type="java.lang.Integer">
<generator class="native" />
</id>

<property name="name" column="name" type="java.lang.String" />
<property name="code" column="code" type="java.lang.String" />
</class>

</hibernate-mapping>

Thanks Jeremy for your answer.

I didn't have problem with a composite map many-to-one, my problem is with the mapping one-to-one with a composite key.

In your case, is like you have a Category class with a composite id, and want to map Product -> Category.

Thanks again, I guess I didn't explain very well in my first post.
Ernesto.