I got one-to-many relationship with Parent -> Child. Default cascade="save-update" in parent.

Parent.getChilds.add(Child1)
Parent.getChilds.add(Child2)

session.save(Parent)

Parent.getChilds.add(Child3)

session.update(Parent)

This works fine. But if I flush it before adding child3 then it creates new child3 but sets child1 & child2 parent to be null !!

So the following code removes the link from the parent.

Parent.getChilds.add(Child1)
Parent.getChilds.add(Child2)

session.save(Parent)
session.flush()
Parent.getChilds.add(Child3)

session.update(Parent)

Though the existing childs are not removed from the collection still hibernate tries to remove the link between parent and child !

I could fix this by making it to bi-directional and inverse="true" but due to requirement I can't do that. I will be happy if someone figures out whats happening here rather than giving alternate solutions.

Have added the mapping :

Parent Mapping

<hibernate-mapping default-cascade="save-update">
<class name="Parent" table="parent" dynamic-insert="false" dynamic-update="false">
<cache usage="nonstrict-read-write" />
<id name="id" type="java.lang.Long" unsaved-value="null">
<column name="ID" sql-type="NUMBER(19)"/>
<generator class="native">
</generator>
</id>
<version name="version" type="int" column="version"/>
<set name="childs" lazy="true" fetch="select" inverse="false">
<cache usage="nonstrict-read-write" />
<key foreign-key="parent_CONTROC">
<column name="parent_FK" sql-type="NUMBER(19)"/>
</key>
<one-to-many class="Child"/>
</set>


Child Mapping

<hibernate-mapping default-cascade="save-update">
<class name="Child" table="child" dynamic-insert="false" dynamic-update="false">
<cache usage="nonstrict-read-write" />
<id name="id" type="java.lang.Long" unsaved-value="null">
<column name="ID" sql-type="NUMBER(19)"/>
<generator class="native">
</generator>
</id>
<version name="version" type="int" column="version"/>


Thanks
K

Anyone ?

Still no one :-(

Any hibernate experts please?

please show Parent.getChilds source, I guess you may be re initializing the collection each time.

From Parent :

private java.util.Collection childs = new java.util.HashSet();

public java.util.Collection getChilds()
{
return this.childs;
}

public void setChilds(java.util.Collection childs)
{
this.childs = childs;
}

And because its unidirectional I have no mapping for Parent in Childs end, as you can see from the mapping in my earlier post.

Just to quick reminder it happens only when you flush and add new child.

are Child1,2,3 new instances or already persistent?

All are new including parent.

all are new inclusing parent and ouy don't save the children first? I don't see any cascading in your mapping file, how can that work?

If you have noticed in the class level, I do have default-cascade set.

And I did tried saving the new child before adding it to the existing collection but no luck.

May be I will make it more clear about the situation :

Parent p = new Parent ();
p.getChilds().add(newchild1);
p.getChilds().add(newchild2);

session.save(p);

session.flush();

Everything is fine up until now.

p.getChilds().add(newchild3);

session.update(p);

Issue:

Now is child3 is persisted and linked to parent but child1 & child2 parents are set to null !

And if I remove the session.flush() all seems fine - unfortunately in the application I can't do this for some reason.