Hello

I am finally getting the hang of hibernate but I cant seem to resolve this simple problem
I am using Xdoclet-1.2.1 Hibernate-2.1.3

I have 2 classes One and Two. I would like a undirectional one-to-one relationship between them. ie I can have a One but no Two but never a Two without a One.

Here are the classes

/**
* @author Marcus
* @hibernate.class table="one"
*
*/
public class One {
private long nid = -1;
private Two two;
/**
*@hibernate.id unsaved-value="-1" generator-class="native"
*/
public long getNid() {
return nid;
}

public void setNid(long nid) {
this.nid = nid;
}

/**
* @hibernate.one-to-one name="ttoo" cascade="all"
*/
public Two getTwo() {
return two;
}
public void setTwo(Two two) {
this.two = two;
}
public void addTwo(Two two) {
two.setOne(this);
this.two = two;
}

/**
* @hibernate.class table="two"
*/
public class Two {
private long nid;
One one;
public Two(){
}

public Two(One one){
this.one = one;
}
/**
*@hibernate.id name="nid" generator-class="foreign"
*@hibernate.generator-param name="property" value="one"
*/
public long getNid() {
return nid;
}

public void setNid(long nid) {
this.nid = nid;
}

/**
*@hibernate.one-to-one name="one" constrained="true"
* @return Value of property party.
*/
public One getOne() {
return one;
}

public void setOne(One one) {
this.one = one;
}
}

And here is the code I am trying to use

One one = new One();
Two two = new Two();
one.addTwo(two);
session.save(one);
session.flush();

One gets saved but two doesnt.
Also here are a few things I have figured out about Xdoclet
1)The name attribute is not supported for one-to-one so no matter what you put it changes it
2)attribute parent-ref is not supported by xdoclet and gives an error

Xdoclet does properly generate the .hbm files and I have no problem uploading the schema to database

Here are the mappings

<class
name="org.marcus.One"
table="one"
dynamic-update="false"
dynamic-insert="false"
>
<id
name="nid"
column="nid"
type="long"
unsaved-value="-1"
>
<generator class="native">
</generator>
</id>

<one-to-one
name="two"
class="org.marcus.Two"
cascade="all"
outer-join="auto"
constrained="false"
/>
</class>

<class
name="org.marcus.Two"
table="two"
dynamic-update="false"
dynamic-insert="false"
>
<id
name="nid"
column="nid"
type="long"
>
<generator class="foreign">
<param name="property">one</param>
</generator>
</id>

<one-to-one
name="one"
class="org.marcus.One"
cascade="none"
outer-join="auto"
constrained="true"
/>
</class>

Now I think I understand the concept behind the one-to-one mappping but obviously I am missing something

Any help would be appreciated

I figured out what I had done wrong. Basically since the primary keys are primitive types I need to explicitly define an unsaved value for both objects.
In this case here is the correct code

/**
* @author Marcus
* @hibernate.class table="one"
*
*/
public class One implements Serializable {
private long nid = -1;

private String www = "";

private Two two;
/**
*@hibernate.id unsaved-value="-1" generator-class="sequence"
*
*/
public long getNid() {
return nid;
}

public void setNid(long nid) {
this.nid = nid;
}

/**
* @hibernate.one-to-one cascade="all"
* @return Value of property userlogin.
*/
public Two getTwo() {
return two;
}

public void setTwo(Two two) {
this.two = two;
}

public void addTwo(Two twwo) {
twwo.setOne(this);
setTwo(twwo);
}
/**
* @hibernate.property
*
*/
public String getWww() {
return www;
}

public void setWww(String www) {
this.www = www;
}

}

/**
* @author Marcus
* @hibernate.class table="two"
*
*/
public class Two implements Serializable{
private long nid = -1;
private One one;
public Two(){
}

public Two(One one){
this.one = one;
}
/**
*@hibernate.id unsaved-value="-1" generator-class="foreign"
*@hibernate.generator-param name="property" value="one"
*
* @return Value of property userlogin.
*/
public long getNid() {
return nid;
}

public void setNid(long nid) {
this.nid = nid;
}

/**
*@hibernate.one-to-one constrained="true"
*
*/
public One getOne() {
return one;
}

public void setOne(One one) {
this.one = one;
}
}

Now the following code works correctly

One one = new One();
Two two = new Two();
one.addTwo(two);
session.save(one);
session.flush();

I hopes this helps others trying to figure this out. It is so simple and a complete example like the one above would have saved so much time.

I do have a few questions about deleting objects.
I had assumed that by doing adding this function to the Class One

public void deleteTwo(){
two=null;
}
and then calling this code in a later session. Assume I have retrieved a previously saved instance of One

one.deleteTwo();
session.save(one);
session.flush();
would delete two.
Obviously I was wrong. I know I can explicitly call session.delete(two). But what happens in the case where an instance of One is retrieved in one session and then passed to a different jvm through rmi where it is altered by calling one.deleteTwo() and then sent back to save its new state. Would I specifically have to do this
if(one.getTwo == null){
session.delete(??);
}

I put the question marks in above because I dont know what to delete. Obviously I cant delete something that is null. Would I have to retrieve a specific instance from the database and then call delete?

I went ahead and tried this code

Session session = HibernateUtil.currentSession();
Transaction tx= session.beginTransaction();
One one = new One();
one.setWww("wooga");
Two two = new Two();
one.addTwo(two);
System.out.println("www is " + two.getOne().getWww());
one.getTwo();
session.save(one);
session.flush();
tx.commit();
HibernateUtil.closeSession();

session = HibernateUtil.currentSession();
tx= session.beginTransaction();
one = (One) session.load(One.class, new Long(1));
System.out.println("www is " + two.getOne().getWww());
one.deleteTwo();
session.save(one);
session.flush();
tx.commit();
HibernateUtil.closeSession();

As I expected two still exists in the database;

What I would like to know is if there is a natural java way to make two not exist anymore.