I have an object ObjectA which has a property Set, having collection of objects ObjectB,

i.e in ObjectA class, i have
private Set objectB = new HashSet();

I want to delete one of the collection objects, "ObjectB", associated with ObjectA
(i.e one of the objects in Set objectB as mentioned above)


--- the mapping from ObjectB to ObjectA is MANY-TO-ONE
--- the associating COLUMN in ObjectB is ObjectAId, as below

--- this is the code of ObjectB Class
/**
* @return com.abc.xyz.ObjectA
*
* @hibernate.many-to-one
* column="ObjectAId"
* not-null="true"
* lazy="false"
* @hibernate.cache usage="read-write"
*/
public ObjectA getObjectA() {
return objectA;
}

Please note that the mapping column attribute,
not-null="true"

what i do is ::

for ( Iterator itr = ObjectA.getObjectB().iterator(); i.hasNext();) {
ObjectBClass objB = (ObjectBClass) itr.next;
if (objB.getName().equals("ABC")) {
itr.remove();
}
}

When i save ObjectA... the following is the error ::

ERROR:
java.sql.SQLException: Cannot insert the value NULL into column 'ObjectAId', table 'Table-OBJECTB'; column does not allow nulls. UPDATE fails.

I understand that when i make the not-null attribute to "false"
it works, i.e. if i do :: not-null="false" it deletes the row in the table.

BUT is there any other way I can delete, without changing the Mapping attribute ??

When I change the not-null="false"
-- it sets the column value of the ObjectB table, to NULL


Please let me know if I can delete, without changing the mapping.

Thanks,
anand

There is no need to save the object when you remove any element from that object's collection.
what you have done is removed the element using iterator.remove(). Thats it. You just need to commit your transaction and the corresponding elelemnt will get deleted from the database.
I have implemented this. It works fine at my end.

Vishal