One-One mapping - Is this right ?

rtadi · **Joined:** Tue Nov 04, 2003 4:20 pm **Posts:** 13

I have a One-to-One mapping example working but not sure if its supposed to be working this way. Can anyone please let me know if the process I'm following is right ?

Code:

// The Persistance Code
Person person = makePerson(); // Faking
Address address = makeAddress(); // Faking
person.setAddress(address);
Integer i = (Integer)session.save(person);
address.setPerson(person);
address.setId(i);
i = (Integer)session.save(address);
// commit transaction

The classes roughly without the setters and getters

Code:

// Parent Class
class Person{
private Address address;
......
}
// Child
class Address{
private Person person;
......
}

The Mapping files. The domain objects have been fine-grained and hence the One-One relationship. Assuming a Person has only one Address, the mappings are :

Code:

// Person Mapping File

<hibernate-mapping>
<class name="Person" schema="TEST" table="PERSON">

<id column="PERSON_ID" name="id" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">PERSON_SEQ</param>
</generator>
</id>

<one-to-one name="address" class="Address" constrained="false" outer-join="false"/> 

<property column="FIRST_NAME" length="30" name="firstName" not-null="true" type="string"/>
<property column="LAST_NAME" length="20" name="lastName" not-null="true" type="string"/>
<property column="SEX" length="7" name="sex" not-null="true" type="string"/>
</class>
</hibernate-mapping>

// Address Mapping

<hibernate-mapping>
<class name="Address" schema="TEST" table="ADDRESS">

<id column="PERSON_ID" name="id" unsaved-value="null"> 
<generator class="assigned" />
</id> 

<property column="ADDRESS1" length="40" name="address1" not-null="true" type="string"/>
<property column="ADDRESS2" length="40" name="address2" type="string"/>
<property column="CITY" length="40" name="city" type="string"/>
<property column="STATE" length="30" name="state" type="string"/>
<property column="ZIP" length="22" name="zip" type="java.lang.Integer"/>

<one-to-one name="person" class="Person" constrained="true" outer-join="auto" /> 
</class>
</hibernate-mapping>

rtadi · **Joined:** Tue Nov 04, 2003 4:20 pm **Posts:** 13

Technically, there should be only one call made to the session with Person populated with Address. Upon commit, the Person record and the Address records have to be created with the foreign key in Address populated with the current Person_Id. The way the above code works, I have to get the CURR_VAL from the Patient and then stick it as the foreign key in Address . The relationship has to be something like this, I guess:

Code:

tx = session.beginTransaction();
Person person = makePerson();
person.setAddress(makeAddress());
Integer i = (Integer)session.save(person);

emmanuel · **Posted:** Wed Nov 05, 2003 7:42 pm

http://www.hibernate.org/118.html#A9

rtadi · **Joined:** Tue Nov 04, 2003 4:20 pm **Posts:** 13

Hi-
I did try to set up my relationships based on the documentation but for some reason it doesn't work. The tests in the Hibernate source has an example with Parent and Child relationship. I used that code as an example and posted the source which works. Can you see if you can come up on top of your head as to what I'm doing wrong. The data model to go with the prior mappings is posted below. Thanks for following up.

Code:

CREATE TABLE PERSON ( 
       PERSON_ID           INTEGER NOT NULL, 
       FIRST_NAME           VARCHAR2(30) NOT NULL, 
       LAST_NAME            VARCHAR2(20) NOT NULL, 
       SEX                  VARCHAR2(7) NOT NULL, 
       BIRTH_DATE           DATE NOT NULL 
); 

ALTER TABLE PERSON 
       ADD  ( PRIMARY KEY (PERSON_ID) ) ; 


CREATE TABLE ADDRESS ( 
       ADDRESS_ID           INTEGER NOT NULL, 
       ADDRESS1             VARCHAR2(40) NOT NULL, 
       CITY                 VARCHAR2(40) NULL, 
       STATE                VARCHAR2(30) NULL, 
       ZIP                  INTEGER NULL, 
       PERSON_ID           INTEGER NULL 
); 

ALTER TABLE ADDRESS 
       ADD  ( PRIMARY KEY (ADDRESS_ID) ) ; 

ALTER TABLE ADDRESS 
       ADD  ( FOREIGN KEY (PERSON_ID) 
                             REFERENCES PERSON 
                             ON DELETE SET NULL ) ; 

emmanuel · **Posted:** Thu Nov 06, 2003 7:13 am

Can't really understand what is your pb.

Code:

<class name="Address" schema="TEST" table="ADDRESS"> 
<id column="PERSON_ID" name="id" unsaved-value="null">
<generator class="foreign">
  <param name="property">person</param>
</generator>
</id>

Will let hibernate assign address id.

rtadi · **Joined:** Tue Nov 04, 2003 4:20 pm **Posts:** 13

It wasn't a problem. I was thinking a save to the Person would create a new record in Address as well but that seems to be not the case. The Address object has also to be saved too. Anyways, I guess I have got a feel for how the One-to-One relationships work. Thanks for your follow ups.

Code:

Person person = makePerson();
Address address = makeAddress();
person .setAddress(address);
session.save(person );
address.setPatient(person );
session.save(address); // Have to save address Object in session too
tx.commit();

emmanuel · **Posted:** Thu Nov 06, 2003 10:51 am

OK I understand now. Try
<one-to-one cascade="save-update" name="address"/>

And try (not related)

Code:

Person person = makePerson();
Address address = makeAddress();
person .setAddress(address);
address.setPatient(person );
session.save(person); // late save to optimize SQL insert
tx.commit(); 

rtadi · **Joined:** Tue Nov 04, 2003 4:20 pm **Posts:** 13

Emmanuel:
That does the trick. Your answer was worth 25 dukes. Thanks so much.