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Hibernate version:

Hello everybody,

I have a super class mapped using annotations as follows:



Then I have a subclass that extends SuperDuperClass and mapped as follows:



The corresponding database tables for the two classes looks like:


SUPER_DUPER
============
* id (PK)
* class_type
* property1
* ......


CHILD_CLASS
==============
* super_duper_id (PK)(FK to the "id" column of table SUPER_DUPER)
* name


Updating ChildClass entities works correctly for ChildClass objects that have *non-null* values for the "name" attribute. The SQL statements generated by Hibernate are follows (and as expected):




However, if I try to update ChildClass entities that have *null* value for the "name" attribute, Hibernate executes that following queries (which are incorrect, I believe):




The ChildClass entity already exists, therefore, when Hibernate tries to execute the "INSERT INTO child_class...." statement, a unique constraints violation is thrown by Oracle on the primary key constraint of the CHILD_CLASS table.

First of all, why is Hibernate executing an INSERT into the secondary table (CHILD_CLASS table in this case) when the ChildClass entity already exists?? Hibernate should have generated and execute and UPDATE statement instead for both the SUPER_DUPER and CHILD_CLASS tables.

Also of interest is that this strange behavior happens for records in the secondary table (CHILD_CLASS) which contains all null values for the non primary key columns. If any of the non primary key columns in the secondary table are non null, Hibernate will update the ChildClass record correctly (i.e. generates UPDATE statements for both the SUPER_DUPER and CHILD_CLASS tables).

Is there something wrong with my annotation mappings? Or is this a bug in Hibernate? Any help would be greatly appreciated.

Thanks.

After some debugging and tracing through Hibernate code (especially the Hibernate class AbstractEntityPersister and its subclasses), I solved the problem by adding the following annotation for the secondary table:


@Entity
@DiscriminatorValue("ChildClass")
@SecondaryTable(name="child_class", pkJoinColumns=@PrimaryKeyJoinColumn(name="super_duper_id"))
@org.hibernate.annotations.Table(appliesTo="child_class", optional=false)
public class ChildClass extends SuperDuperClass {

private String name;

public String getName() {
return this.name;
}

public void setName(String name) {
this.name = name;
}

}


The @org.hibernate.annotations.Table attribute "optional" will tell Hibernate to use an outer join. Most importantly, "optional=false" will also tell Hibernate to update the row in the secondary table instead of inserting a new row.