Setting a 1:1 association with "mapped-by"

Jörg von Frantzius Wed, 17 May 2006 08:40:34 -0700

Hello JDO experts,

when writing some JUnit test today I came across an interesting phenomenon. I have two classes A and B with a 1:1 association between them. The FK is put on class A, and the corresponding field on B has "mapped-by" with the corresponding field on A (see metadata below).

Now when I have the following object graph:

and perform the operation

a1.setB_1to1(b2)

then I'd expect the object graph to look like the following:

In particular, I'd expect a2 not pointing to b2 anymore, as this clearly is supposed to be is a 1:1 relationship. The implementation can determine this being a 1:1 association, as there are two corresponding fields, and consequently it should issue

"UPDATE A SET B_1TO1_FK=NULL WHERE B_1TO1_FK=2"

before

"UPDATE A SET B_1TO1_FK=2 WHERE ID=1"

to keep this being a 1:1 association.

However, what I end up with in the database is:

Does this really work as expected?

Here's the metadata:

        <class name="A" identity-type="application" table="A" detachable="true"
            objectid-class="javax.jdo.identity.LongIdentity"
            persistence-modifier="persistence-capable">
            <inheritance strategy="new-table"/>
            <version strategy="version-number" column="jdoversion"/>
            <field name="id" primary-key="true" persistence-modifier="persistent" value-strategy="sequence" sequence="A_SEQ" >
                <extension vendor-name="jpox" key="key-database-cache-size" value="100"/>
            </field>

            <field name="b_1to1" column="b_1to1_FK"
                persistence-modifier="persistent" >
            </field>
        </class>

        <class name="B" identity-type="application" table="B" detachable="true"
            objectid-class="javax.jdo.identity.LongIdentity"
            persistence-modifier="persistence-capable">
            <inheritance strategy="new-table"/>
            <version strategy="version-number" column="jdoversion"/>
            <field name="id" primary-key="true" persistence-modifier="persistent" value-strategy="sequence" sequence="B_SEQ" >
                <extension vendor-name="jpox" key="key-database-cache-size" value="100"/>
            </field>

            <field name="a_1to1" mapped-by="b_1to1"
                persistence-modifier="persistent" >
            </field>
        </class>

Regards,
Jörg

P.S.
I hope the pictures survived...

Setting a 1:1 association with "mapped-by"

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