one-to-one basic OR.....please help.........

mooki · **Joined:** Thu Aug 12, 2004 9:32 am **Posts:** 17

Hibernate version:2.1.6

Hi,
I know it's a basic stuff what im about to ask but I cannot understand this ......

I have ClassA containing ClassB and what I need is, that when creating class A It will insert 2 records (classA table and ClassB table)

ClassA (has no id property)
private x
private y
private classBinstance ClassB

ClassB
private id
private z

tables:

Code:

   TABLE ClassA
        CLASSA_ID char(32),
        X ...
        y...
        

   TABLE ClassB
       CLASSB_ID number(10),
       CLASSA_ID char(32),
        Z...

mapping:

Code:

    <class name="ClassAr" table="CLASSA">
       <id type="string" unsaved-value="null" access="field">
           <column name="CLASSA_ID" sql-type="char(32)" not-null="true"/>
                <generator class="uuid.hex"/>
       </id>
        <one-to-one name="classBinstance" class="ClassB" cascade="all" constrained="true"/>
    </class>


   <class name="ClassB" table="CLASSB">
       <id name="id" type="long" unsaved-value="null" access="field">
           <column name="CLASSB_ID" sql-type="number(10)" />
                <generator class="assigned"/>
       </id>
       ...
       ...
    </class>

now when I tried
cb ClassB = new ClassB();
ca ClassA = new ClassA(cb); //sets the inner property

storage.save(ca);

If FAILED ON UPDATE CLASS B !!!!
I saw
Insert into ClassA......
Update ClassB (when it did not insert it there yet).....

Is that mapping is right ?
i did not understand if i should put the class="foreign" in generator and where.....

help ? anyone ????

emmanuel · **Posted:** Mon Sep 06, 2004 12:16 pm

either do
* s.save(b) to help Hibernate to know this is an insert and not an Update
* use foreign generator in B and add b.getA() to refer to
* set unsaved-value of B to any (you'll have to do s.update() by hands however)
* and my favorite add a version number to B and put unsaved-value=null inside it. Hibernate will be able to know wheter B is new or already eprsisted

mooki · **Joined:** Thu Aug 12, 2004 9:32 am **Posts:** 17

Setting version required me to change the class and add a version property.

I am trying to change the software architecture as minimum as possible.
however define mapping and the changes in the database are more acceptable.

When I saved class B is was OK.
then I saved class A and it was OK

the problem is that in one-to-one relation it is using the primary_id for the relation, so when read classA it tried reading classB using comparison of both ID's which are different.

I can use property-ref but as I mentioned I dont want to add any properties to the class......

In many-to-one you can define column and not "property" how come i cannot do that in one-to-one ???? or is there different way to do that ???

Isn't it possible that I will just have a column ( classBid ) in classA table,
and when i will save classA it will update the ID of classB in it, AND when i will read classA it will read classB using its classBid column ????

markku · **Joined:** Fri Sep 17, 2004 3:07 pm **Posts:** 14

Had a pretty similar problem with some code based on the Hibernate ref doc example.

This helped me (using the unique foreign key approach):
- cascade="all" in the mapping of the "parent" object you intend to save
- in addition to the many-to-one declaration in the "child" object mapping, declare the foreign key field itself (hibernate will not complain if missing)

Perhaps add these to the doc examples, Hibernate team ?

//markku

markku · **Joined:** Fri Sep 17, 2004 3:07 pm **Posts:** 14

Oh yes, and set the child-to-parent relationship in addition to parent-child.

//m

pv · **Posted:** Sun Sep 19, 2004 7:50 am

Hi.

I have similar problem (actually with my head :-)).

Can you show me solution of this problem (<one-to-one> bidirectional mapping)? I mean all java bean definiton code, SQL DDL, hiberanate mapping file and Java code between sessionFactory.openSession() and session.close()

Thanks very much.

Petr

mooki · **Joined:** Thu Aug 12, 2004 9:32 am **Posts:** 17

I think it is uni-direction only but maybe you can expand that.....

Mapping:

Code:

    <class name="ProcessManager" table="ProcessManager">
       <id type="string" unsaved-value="null" access="field">
           <column name="Process_Def_Id" sql-type="char(32)" not-null="true"/>
                <generator class="foreign">
                   <param name="property">processDefinition</param>
                </generator>
       </id>
        <property name=
        ...
        ...
        ...
        <one-to-one name="processDefinition"  class="ProcessDefinition" cascade="all" constrained="true"/>
    </class>


    <class name="ProcessDefinition" table="ProcessDefinition">
       <id type="string" unsaved-value="null" access="field">
           <column name="Process_Def_ID" sql-type="char(32)" not-null="true"/>
                <generator class="uuid.hex"/>
       </id> 
       <property name="processId"
       ....
       ....
       ....

    </class>

DATABASE:

Code:

Create table ProcessManager (
       process_Def_ID       char(32),
       other_properties......


create table ProcessDefinition (
     Process_Def_ID    char(32),
     processId            number(10),
     other_properties.....

Nir

pv · **Posted:** Sun Sep 19, 2004 11:29 am

to mooki

Thank You Very Much.

Unfortunately, I found out that my problems are not in mapping (only).
I dont want pollute this forum by my stupid question. Would it be possible discus by email? My @ is in my profile.