one-to-one relationship with same comp primary key

eivindt · **Posted:** Fri Oct 28, 2005 5:17 am

I've got two tables, TableParent and TableChild:

Code:

+---------------+             +----------------+
| TableParent   |             | TableChild     |
+---------------+             +----------------+
| Composed   PK |-------------| Composed PK/FK |
| Key        PK |             | Key      PK/FK |
| Attribute     |             | ChildAttribute |
+---------------+             +----------------+

As you can see, TableChild's primary key is the foreign key from TableParent.

I guess I should have made a mapping file describing this as TableChild extending TableParent, but I didn't, in stead I defined this as a one-to-one mapping:

TableParent.hbm.xml:

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >  
<hibernate-mapping>
<class 
    name="error.demo.hibernate.composite_keys.model.TableParent" 
    table='"TableParent"'
>
    <meta attribute="implement-equals" inherit="false">true</meta>
    <composite-id name="comp_id" class="error.demo.hibernate.composite_keys.model.TableParentPK">
        <key-property 
            name="composed" 
            column="Composed" 
            type="long"
            length="10"
        />
        <key-property 
            name="key" 
            column="Key" 
            type="long"
            length="10"
        />
    </composite-id>    
    <property
        name="attribute"
        type="java.lang.Long"
        column="Attribute"
        length="10"
    />
    <one-to-one
        name="tableChild"
        class="error.demo.hibernate.composite_keys.model.TableChild"
        outer-join="auto"
    />

</class>
</hibernate-mapping>

TableChild.hbm.xml:

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<hibernate-mapping>
<class 
    name="error.demo.hibernate.composite_keys.model.TableChild" 
    table='"TableChild"'
>
    <meta attribute="implement-equals" inherit="false">true</meta>
    <composite-id name="comp_id" class="error.demo.hibernate.composite_keys.model.TableChildPK">
        <key-property 
            name="composed" 
            column="Composed" 
            type="long"
            length="10"
        />
        <key-property 
            name="key" 
            column="Key" 
            type="long"
            length="10"
        />
    </composite-id>    
    <property
        name="childAttribute"
        type="java.lang.String"
        column="ChildAttribute"
        length="19"
    />
    <one-to-one
        name="tableParent"
        class="error.demo.hibernate.composite_keys.model.TableParent"
        outer-join="auto"
        constrained="true"
    />
</class>
</hibernate-mapping>

So far so good, no complaints when configuring hibernate. But if I manually insert a row in TableParent and TableChild, and ask hibernate to load this row, using

Code:

         TableParentPK pk = new TableParentPK(1,2);
         TableParent pi = (TableParent) s.load(TableParent.class, pk);

I get an ugly ClassCastException, deep down in CGLIB:

Code:

Exception in thread "main" java.lang.RuntimeException: net.sf.hibernate.PropertyAccessException: exception getting property value with CGLIB (set hibernate.cglib.use_reflection_optimizer=false for more info) getter of error.demo.hibernate.composite_keys.model.TableParentPK.?
   at error.demo.hibernate.composite_keys.CompositeKeyErrorDemo.main(CompositeKeyErrorDemo.java:41)
Caused by: net.sf.hibernate.PropertyAccessException: exception getting property value with CGLIB (set hibernate.cglib.use_reflection_optimizer=false for more info) getter of error.demo.hibernate.composite_keys.model.TableParentPK.?
   at net.sf.hibernate.type.ComponentType.getPropertyValues(ComponentType.java:193)
   at net.sf.hibernate.type.ComponentType.nullSafeGetValues(ComponentType.java:164)
   at net.sf.hibernate.type.ComponentType.nullSafeSet(ComponentType.java:151)
   at net.sf.hibernate.loader.Loader.bindPositionalParameters(Loader.java:753)
   at net.sf.hibernate.loader.Loader.prepareQueryStatement(Loader.java:793)
   at net.sf.hibernate.loader.Loader.doQuery(Loader.java:269)
   at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:138)
   at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:941)
   at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:961)
   at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:59)
   at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:51)
   at net.sf.hibernate.persister.EntityPersister.load(EntityPersister.java:413)
   at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:2131)
   at net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:2001)
   at net.sf.hibernate.impl.SessionImpl.internalLoad(SessionImpl.java:1963)
   at net.sf.hibernate.type.OneToOneType.resolveIdentifier(OneToOneType.java:71)
   at net.sf.hibernate.type.EntityType.resolveIdentifier(EntityType.java:208)
   at net.sf.hibernate.impl.SessionImpl.initializeEntity(SessionImpl.java:2219)
   at net.sf.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:319)
   at net.sf.hibernate.loader.Loader.doQuery(Loader.java:309)
   at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:138)
   at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:941)
   at net.sf.hibernate.loader.Loader.loadEntity(Loader.java:961)
   at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:59)
   at net.sf.hibernate.loader.EntityLoader.load(EntityLoader.java:51)
   at net.sf.hibernate.persister.EntityPersister.load(EntityPersister.java:413)
   at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:2131)
   at net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:2001)
   at net.sf.hibernate.impl.SessionImpl.load(SessionImpl.java:1930)
   at error.demo.hibernate.composite_keys.CompositeKeyErrorDemo.main(CompositeKeyErrorDemo.java:39)
Caused by: java.lang.ClassCastException
   at error.demo.hibernate.composite_keys.model.TableParentPK$$BulkBeanByCGLIB$$6222dd4a.getPropertyValues(<generated>)
   at net.sf.cglib.beans.BulkBean.getPropertyValues(BulkBean.java:86)
   at net.sf.hibernate.type.ComponentType.getPropertyValues(ComponentType.java:190)
   ... 29 more

If I replace the TableChildPK with a TableParentPK, then it works, but shouldn't this work as well? (the mapping files were originally generated by middlegen, that's why the PK classes are two separate classes in the first place)

Hibernate version: 2.1.8

Eivind

kgignatyev · **Posted:** Fri Oct 28, 2005 10:52 am

According to
http://www.hibernate.org/hib_docs/v3/re ... n-onetoone
the classes should have the same PK, or have many-to-one mapping even it is one-2-one business wise

eivindt · **Posted:** Fri Oct 28, 2005 6:15 pm

Sorry for being dense, I'd just like to make sure I really understand this. The docs say:

Quote:

Primary key associations don't need an extra table column; if two rows are related by the association then the two table rows share the same primary key value. So if you want two objects to be related by a primary key association, you must make sure that they are assigned the same identifier value!

As seen from the database, these two rows do share the same primary key value. So I guess the above text refers to the Java primary key, i.e. the PK must be the same value and PK-class, right?

That also explains why this isn't a problem for a relation between two classes without composite PKs, since these automatically shares the same primary key class.

Eivind

kgignatyev · **Posted:** Fri Oct 28, 2005 6:18 pm

correct

eivindt · **Posted:** Fri Nov 04, 2005 9:48 am

I've changed my mapping files according to your advice. TableParent.hbm.xml is unchanged, while TableChild.hbm.xml now looks like:

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
    
<hibernate-mapping>

<class 
    name="error.demo.hibernate.composite_keys.model.TableChild" 
    table='"TableChild"'
>
    <meta attribute="implement-equals" inherit="false">true</meta>

    <composite-id name="comp_id" class="error.demo.hibernate.composite_keys.model.TableChildPK">
        <key-property 
            name="composed" 
            column="Composed" 
            type="long"
            length="10"
        />
        <key-property 
            name="key" 
            column="Key" 
            type="long"
            length="10"
        />
    </composite-id>    

    <property
        name="childAttribute"
        type="java.lang.String"
        column="ChildAttribute"
        length="19"
    />

     <many-to-one
        name="tableParent"
        class="error.demo.hibernate.composite_keys.model.TableParent"
        unique="true"
      insert="false"
      update="false"
    >
        <column name="composed" />
        <column name="key" />
    </many-to-one>

</class>
</hibernate-mapping>

Unfortunately, I'm still getting the same error:

Am I still doing something wrong?

I have a complete simple test program if that's useful.

Eivind

kgignatyev · **Posted:** Fri Nov 04, 2005 11:28 am

send it to me please.

kgignatyev · **Posted:** Fri Nov 04, 2005 6:40 pm

TableChild should use TableParentPK as PK