hi. pls need help with hibernate with joined subclasses. if i get object (PorC - is parent for person and company) directly using session.get() i can use instanceof to determine which object from joined subclasses it is (if person or company). but if i get to that object through relation e.g from address /mapped many to one/ i can get only object PorC and i am not able to determine which joined subclass it is /person or company/. if i try to change object /recast/ to person /i know that that address belongs to person/ system generate error classcastexception

any advice pls?

mapping of joined subclasses:

<hibernate-mapping>

<class name="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.PCRDTO" table="paPCRNew.pcr">

<id name="PCRId" column="PCRId" type="java.lang.Integer">

<generator class="native">


</generator>
</id>
<many-to-one name="source" class="sk.bantip.productiv.Main.Source.MVC.Main.bin.Source.SourceDTO" cascade="none" outer-join="auto" update="true" insert="true" column="sourceid"/>
<property name="isVisible" type="java.lang.String" update="true" insert="true" column="isVisible"/>
<many-to-one name="mutator" class="sk.bantip.productiv.Main.Source.MVC.Main.bin.User.UserDTO" cascade="none" outer-join="auto" update="true" insert="true" column="mutatorid"/>
<property name="mutatorTS" type="java.util.Date" update="true" insert="true" column="mutatorTS"/>
-
<set name="address" lazy="true" inverse="true" cascade="all-delete-orphan" sort="unsorted">
<key column="pcid">
</key>
<one-to-many class="sk.bantip.productiv.Main.Source.MVC.AC.bin.Address.AddressDTO"/>
</set>
-
<set name="contact" lazy="true" inverse="true" cascade="all-delete-orphan" sort="unsorted">
<key column="pcrid">
</key>
<one-to-many class="sk.bantip.productiv.Main.Source.MVC.AC.bin.Contact.ContactDTO"/>
</set>
-
<set name="label" lazy="false" inverse="true" cascade="all-delete-orphan" sort="unsorted">
<key column="pcrid">
</key>
<one-to-many class="sk.bantip.productiv.Main.Source.MVC.Label.bin.Label.LabelDTO"/>
</set>

<joined-subclass name="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.RelationDTO" table="paPCRNew.relation">
<key column="relationid"/>
<many-to-one name="person" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.PersonDTO" cascade="none" outer-join="auto" update="true" insert="true" column="personid"/>
<many-to-one name="company" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.CompanyDTO" cascade="none" outer-join="auto" update="true" insert="true" column="companyid"/>
<many-to-one name="position" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.Position.PositionDTO" cascade="none" outer-join="auto" update="true" insert="true" column="positionid"/>
<property name="isDefaultPerson" type="java.lang.String" update="true" insert="true" column="isDefaultPerson"/>
</joined-subclass>
-
<joined-subclass name="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.CompanyDTO" table="paPCRNew.company">
<key column="companyid"/>
<property name="name" type="java.lang.String" update="true" insert="true" column="name"/>
-
<set name="relation" lazy="true" inverse="true" cascade="all-delete-orphan" sort="unsorted">
<key column="companyid">
</key>
<one-to-many class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.RelationDTO"/>
</set>
</joined-subclass>
-
<joined-subclass name="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.PersonDTO" table="paPCRNew.person">
<key column="personid"/>
<property name="lastName" type="java.lang.String" update="true" insert="true" column="lastName"/>
<property name="firstName" type="java.lang.String" update="true" insert="true" column="firstName"/>
<property name="van" type="java.lang.String" update="true" insert="true" column="van"/>
<property name="initials" type="java.lang.String" update="true" insert="true" column="initials"/>
<many-to-one name="titleFirst" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.TitleFirst.TitleFirstDTO" cascade="none" outer-join="auto" update="true" insert="true" column="titlefirstid"/>
<many-to-one name="titleLast" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.TitleLast.TitleLastDTO" cascade="none" outer-join="auto" update="true" insert="true" column="titlelastid"/>
-
<set name="relation" lazy="true" inverse="true" cascade="all-delete-orphan" sort="unsorted">
<key column="personid">
</key>
<one-to-many class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.RelationDTO"/>
</set>
</joined-subclass>
</class>
</hibernate-mapping>



and address mapping

<hibernate-mapping>
-
<class name="sk.bantip.productiv.Main.Source.MVC.AC.bin.Address.AddressDTO" table="paac.address">

<id name="addressId" column="addressId" type="java.lang.Integer">

<generator class="native">


-->
</generator>
</id>
<many-to-one name="pcr" class="sk.bantip.productiv.Main.Source.MVC.PCR.bin.PCR.PCRDTO" cascade="none" outer-join="auto" update="true" insert="true" column="PCId"/>
<property name="isDefaultAddress" type="java.lang.String" update="true" insert="true" column="isDefaultAddress"/>
<property name="type" type="java.lang.String" update="true" insert="true" column="type"/>
<property name="street" type="java.lang.String" update="true" insert="true" column="street"/>
<property name="zip" type="java.lang.String" update="true" insert="true" column="zip"/>
<property name="city" type="java.lang.String" update="true" insert="true" column="city"/>
<property name="province" type="java.lang.String" update="true" insert="true" column="province"/>
<property name="country" type="java.lang.String" update="true" insert="true" column="country"/>
<many-to-one name="source" class="sk.bantip.productiv.Main.Source.MVC.Main.bin.Source.SourceDTO" cascade="none" outer-join="auto" update="true" insert="true" column="sourceid"/>
<many-to-one name="mutator" class="sk.bantip.productiv.Main.Source.MVC.Main.bin.User.UserDTO" cascade="none" outer-join="auto" update="true" insert="true" column="mutatorid"/>
<property name="mutatorTS" type="java.util.Date" update="true" insert="true" column="mutatorTS"/>

</class>
</hibernate-mapping>

I also had the same problem.
This is because the associated object is proxyed by hibernate and is in reality of type "<base-class-type>$$EnhancerByCGLIB$$<some-hex-value>"

The only solution that I know to this problem is to declare the association lazy="false" so that the associated object is not proxyed, but this is not always a satifying solution.

Pascal Jacob.

I too am having the same problems. On most relationships, I get back the real object but there's a select few relationships where I get back the proxy object and it causes havoc. Not only in my code by I can't merge it back into the EntityManager to save changes either (I'm using EJB 3.0).

I find it frustrating that I can't find more definitive information on what is going on and how to find an optimal solution.

From my experience there are only two sure ways to solve this: using lazy=false, or using JOIN FETCH queries, although these can introduce problems of their own.

I don't like using EAGER relationships when I don't have to however the few places where I am having trouble are on N-to-1 relationships so it shouldn't have a lot of unnecessary objects being loaded.

I find it interesting that Hibernate folks themselves suggest setting lazy=false as a solution to this when elsewhere in their documentation they strongly suggest avoiding eager relationships since they may load too many unneeded objects -- possibly the entire database in a worst case scenario.

I wish I could find a better solution but so far I can't.