I have read through the manual and didn't find a solution for this. using Hibernate 3.0 and eclipse 3.1 M5 in my case.

I have two classes Parent and Child, using the same primary key for association. The Parent class primary key is "assigned" using sequence. The Child class should use the same key as primary key. The Child class contains no reference property to Parent class.

<class name="Parent" table="PTable">
<id column="pid">
<generator class="sequence">
<param name="sequence">parent_seq</param>
</generator>
</id>
<one-to-one name="child" class="Child"/>
<property name="other_prop" ....></property>
</class>

<class name="Child" table="CTable">
<id column="pid">
<generator class="foreign">
<param name="property">Parent</param>
</generator>
<property name="child_other_prop" ... ></property>
</class>

My question is without Child class property reference to Parent, How could I still write a valid mapping file. Currently the mapping file for Child class will result in Exception "cannot resolve property [name=Parent] to corresponding index". I understand it is because the generator cannot find the Parent reference property in Child class. But how could I work around this? The class is pre generated in castor and table is defined as well to satisfy 3NF etc. Without freedom to change either class/table definition, could I still write a valid hbm.xml?

thanks in advance,

edmond

reformatted the xml mapping part here.

I think parent.hbm.xml should like that:

<class name="Parent" table="PTable">
<id column="pid">
<generator class="sequence">
<param name="sequence">parent_seq</param>
</generator>
</id>
<one-to-one name="child" class="Child" constrained="true"/>
<property name="other_prop" ....></property>
</class>

Yuan,

It is still the same error. I thought the constrained attr should be in Child class if the Parent to Child is 1:0/1 relationship. But anyway, the Exception is still property cannot be resolved in Child class id foreign generator

As I understand it the "param" entry, it is not a property declaration, it is only a property reference. Therefore the child needs a property named "parent" for it to refer to.

Parent-mapping.xml:



Child-mapping.xml:



With both of these property declarations in place your param setting should be fine.

_evan

Evan,

My situation is that the code was generated with castor source generator and it is not likely I can alter the Child class definition to add a property "parent". Can I still get a working hibernate mapping?

thanks,

Yes, but perhaps not with "foreign".

The definition of "foreign" in the reference docs is "uses the identifier of another associated object." There must be an association.

Can your generator make two passes? Can you live with the hassle of using the "assigned" generator on the child?

I am not sure I understand how, in a correct domain model, an object (child) can be dependent upon another object (parent) to establish uniqueness, yet cannot navigate to that object (child --> parent).

Evan

Here I am using foreign generator, not foreign key. The association is through primary key. The Parent class primary key is via DB sequence generator, the Child class primary key is "foreign". Neither Child/Parent defined a property for such primary key. Ususally this can be done using composition and store both Child/Parent into the same table, but I cannot, since I need to store them into two tables (PTable/CTable).