I have some problems figuring out how to use the <join> element in Hibernate3. Suppose I have two tables Person and Addres. Address table has a column Id, and Person has a column AdrsId, which references Id column in the Address table. I am trying to get Hibernate to join Address row with Person row and map the result to an object of the Person class.

I tried:

<class name="Person" table="Person">
<id name="Id" column="Id" />

<join table="Address" >
<key column="Id" />
</join>
</class>

But it generates a query, which joins Person.Id with Address. Id instread of Person.AdrsId and Address.Id

If I do:

<class name="Person" table="Person">
<id name="Id" column="Id" />

<join table="Address" >
<key column="AdrsId" />
</join>
</class>

But it generates a query, which joins Person.Id with Address. AdrsId instread of Person.AdrsId and Address.Id


Do I need to add a many-to-one element inside the join element? If I do, then is there a way to avoid mapping a property inside the Person class to AdrsId column?

Thanks.

<key property-ref="..."/> is is not yet possible for <join> in HB3.

Why on earth would you ever want to map address data into the customer class?! Just create an Address class. Much more OO.

I used a hypothetical example in order to better explain what I needed to do.

In reality we have to change (normalized) the old schema, but don't want to rewrite the HQL queries already written for the old schema. So, we desided to use <join> to map the new tables to the old classes, which will (hopefully) allow us to leave the HQL queries intact.

If I can't use <join>, what are my other alternatives?

Thanks.

Well, if you have control of the schema, a better relational model would reverse the direction of the FK. Then you can use <join>.

(Unless multiple Person rows can share the same Address row.)

Yes, multiple persons can share the same address in our new schema.

So, how can we map the new tables to the old classes so that we don't have to change HQL queries?