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StefanKNeedsHelp
 Post subject: Table per Subclass - Child added in Parent Table?!
PostPosted: Mon Mar 08, 2010 6:04 am 
Beginner
Beginner

Joined: Thu Nov 26, 2009 8:20 am
Posts: 23
Hello,
I have a simple structure:
XYDiagram extends Diagram extends DiagramBase.
I want Hibernate to use the Table-per-Subclass inheritance strategy.
Everything is working fine so far but hibernate persists the child objects in the parent table.

Example:

I have an object of the type XYDiagram. I want to persist it. Hibernate inserts the object in the Table DiagramBase and not in the table XYDiagram (which exists!!).

My mapping files are:

Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <subclass
        name="...Diagram"
        extends="...DiagramBase">
       
    </subclass>

</hibernate-mapping>


Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class
        name="DiagramBase"
        table="DIAGRAMBASE">
       
        <id
            name="id"
            column="DIAGRAMBASE_ID">
            <generator class="native"/>
        </id>

      <discriminator column="DTYPE"/>

        <property
            name="name"
            column="DIAGRAM_NAME"/>
       
        <property
            name="lockUser"
            column="DIAGRAM_LOCK_USER"/>
       
        <property
            name="lockTimeStamp"
            column="DIAGRAM_LOCK_TIMESTAMP"/>
           
    </class>

</hibernate-mapping>


Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <joined-subclass
           name="XYDiagram"
        extends="Diagram"
        table="xydiagram">
       
        <key column="DIAGRAM_ID" foreign-key="DIAGRAMBASE_ID"></key>
       
    </joined-subclass>

</hibernate-mapping>


I would appreciate any help!

Thanks in advance & best regards
Alex
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pb00067
 Post subject: Re: Table per Subclass - Child added in Parent Table?!
PostPosted: Mon Mar 08, 2010 6:23 am 
Expert
Expert

Joined: Tue Jun 16, 2009 3:36 am
Posts: 990
Actually with joined-subclass (Table per Subclass) strategy there should as well an insert in the
parent class (the common attributes) as too in the child-table (the child-specific attributes).
If you want to have just one insert in the apposite child-table,
then you must opt for union-subclass strategy indeed.
BTW: In your example you are mixing 'subclass' with 'joined-subclass' strategies within the same class hierarchy.
Be aware that not all kind of strategy mixtures are always guaranteed to be working.
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StefanKNeedsHelp
 Post subject: Re: Table per Subclass - Child added in Parent Table?!
PostPosted: Mon Mar 08, 2010 7:12 am 
Beginner
Beginner

Joined: Thu Nov 26, 2009 8:20 am
Posts: 23
First, thanks for your answer!

I tried to define the subclasses only in my parent classes xml-file, but it doesn't work.
Hibernate is inserting all XYDiagrams in the DiagramBase table.
Do I need some special tags for inserting the childs in another table?

Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class
        name="DiagramBase"
        table="DIAGRAMBASE">
       
        <id
            name="id"
            column="DIAGRAMBASE_ID">
            <generator class="native"/>
        </id>

      <discriminator column="DTYPE"/>

        <property
            name="name"
            column="DIAGRAM_NAME"/>
       
        <property
            name="lockUser"
            column="DIAGRAM_LOCK_USER"/>
       
        <property
            name="lockTimeStamp"
            column="DIAGRAM_LOCK_TIMESTAMP"/>
           
         <set name="diagramElements" cascade="all-delete-orphan" lazy="false">
           <key><column name="DIRECT_DIAGRAM_PARENT_FK_ID"></column></key>
           <one-to-many class="DiagramElement"/>
         </set>
         
         <subclass name="XYDiagram" discriminator-value="XYDiagram">
             <join table="xydiagram">
                <key column="DIAGRAM_ID"/>
            </join>
        </subclass>
         
       <subclass
              name="Diagram"
              extends="DiagramBase">
       
       </subclass>
            
    </class>

</hibernate-mapping>
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StefanKNeedsHelp
 Post subject: Re: Table per Subclass - Child added in Parent Table?!
PostPosted: Mon Mar 08, 2010 8:12 am 
Beginner
Beginner

Joined: Thu Nov 26, 2009 8:20 am
Posts: 23
Hello again,
sorry I misunderstood your post first.
I solved the problem by defining explicit sql-insert statements in the subclasses...

Thanks for your advice :)
Best regards, Alex
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