Hibernate version: 3.0

Mapping documents:

I am trying to map a unidirectional one to one association between Person and Address (a person has one address) where the personId PK from Person is present as a FK in the Address table.

<class name="Person">
<id name="id" column="personId">
<generator class="native"/>
</id>
<one-to-one name="address"
class="org.compname.Address"
property-ref="personId"
/>
</class>

<class name="Address">
<id name="id" column="addressId">
<generator class="native"/>
</id>
<property name="personId" column="personId" not-null="true" insert="false" update="false" />
</class>

create table Person ( personId bigint not null primary key)
create table Address ( addressId bigint not null primary key, personId bigint not null unique )


Code between sessionFactory.openSession() and session.close():

(using spring hibernate template)
getHibernateTemplate().saveOrUpdate(person);

Full stack trace of any exception that occurs:

Null id in entry. Cannot insert row with person_id null...

Name and version of the database you are using:
SQL Server 2000

The generated SQL (show_sql=true):

update Address set personId = null where id = ?


I am able to load up the address and update it but if i try to insert it i get the error that null not allowed in personId for the Address table. Its like its not carrying the id from the Person down into the child address object.

Help!

I guess you have to tell Hibernate about the relationship in the class whose table has the fk.

so make it bidirectional then? See i dont want to do that... i also dont want to have a person object to the address class. I still dont get the need for bidirectional relationships. Maybe what I am trying to do it doesnt make sense for... maybe there are better examples for why its needed. I just dont get it..

Hi

How about the below mapping?

Mapping for Parent <class name="Person">
<id name="id" column="personId">
<generator class="native"/>
</id>
<one-to-one name="address" class="org.compname.Address" cascade="all"></one-to-one>
</class>

Mapping for Child
<class name="Address">
<id name="id" column="addressId">
<generator class="foreign">
<param name="property">personId</param>
</generator>
</id>
<one-to-one name="personId" class="org.compname.Person" constrained="true"></one-to-one>
</class>

For more info on unidirectional one-to-one association look in to this
http://www.hibernate.org/hib_docs/v3/re ... tional-121

And one Question?
Why do u use SaveOrUpdate when you clearly know that what action you have to perfom i.e) insert or update?

I think its wise to use SaveOrUpdate when you are not sure that the record is in the DataBase or not.

I read up in the docs (http://www.hibernate.org/hib_docs/v3/reference/en/html/associations.html#assoc-unidirectional-121).

I think you have to use a many-to-one with unique="true".
As far as I can tell, a unidirectional one-to-one only works for the table where the fk resides.
[/url]

i'll try tomorrow when i get to work.. thanks ramnath...

btw i'm using saveOrUpdate because i'm just prototyping... also i have an extremely large object map (40+ objects) that is multiple levels deep ... a bunch of one-to-many, one-to-one and components... Usually after manipulating several items in the object map i sent the top level parent to hibernate to persist. I want it to handle what has been changed/added... so even more reason to use saveOrUpdate.

now, having said that... if i'm doing a simple change to one object.. sure i'll just save just that one and call "update".


hhuber, i tried doing the many-to-one with the unique="true" and it still didnt work.. same error.

nope that didnt work. Any other ideas?

I looked back in the reference ([url=file:///c:/Program%20Files/dev/db/hibernate/hibernate-3.0/doc/reference/en/html/associations.html#assoc-unidirectional-12m]8.2.3. one to many[/url]). This seems to match your DDL.
The one-to-one (or many-to-one as I proposed before) have different DDL from yours.

The drawback is you have to use a set. But you could make the accessors for the set private and expose only the getter-setter interface for a single object.


We've got a simular table layout in our application. We made the relationship bidirectional with a one-to-one in the parent and a unique many-to-one in the child table.


Perhaps that helps,
Heinz

Sorry, the link is a local one. Here the correct link: http://www.hibernate.org/hib_docs/v3/reference/en/html/associations.html#assoc-unidirectional-12m

hhuber,

We are faced with the same problem - would seem that there may be a problem with the one-to-one associations and Hibernate performing all related inserts. So your using the one-to-one and a unique many-to-one in the child table essentially creates the one-to-one correct? You still had to use a set though, is that correct?

Michelle

Well, we've just started the development, so this far, we're only reading the database. But this works perfectly ;-)

We didn't have to use a set.
We have a nullable one-to-one association on the parent side.
The foreign key and the many-to-one are on the detail side.
Both associations are mode with the correct object. No need to use a set since we don't have any *-to-many.

We'll try inserting and updating soon. You'll probably hear from me (somewhere in the forum), if it doesn't work :-)

hth,
Heinz