Cascading parent/child inserts while avoiding uniqueness constraints

Question

Assume that I have two classes that I'd like to persist: MyObject and
InternalObject. MyObject has an InternalObject field. That is, MyObject is
the parent, InternalObject is the child in this one-to-one relationship.
Steps involved:
1) Enable ForeignKeyConstraints property in kodo.properties. That is add
the line,
kodo.jdbc.ForeignKeyConstraints=true
2) In package.jdo, add the following kodo extensions for MyObject's
InternalObject field mapping, i.e., io in my case.
<field name="io" default-fetch-group="false">
<extension vendor-name="kodo" key="jdbc-delete-action"
value="cascade"/>
<extension vendor-name="kodo" key="dependent" value="true"/>
</field>
The reasons that we have done these steps: we'd like kodo to properly
re-order the sql statements if necessary in order not to violate
parent/child dependencies during insertion, and also force cascading
deletes in case we delete the parent object.
Now comes the bulk of the algorithm.
String sKey // key of the object to insert
String sValue //value of the object to insert
MyObject o = new MyObject(sKey, sValue);
InternalObject io = new InternalObject(sKey,sValue); //using same values :)
o.setInternalObject(io); //parent-child relation
Object id = ((PersistenceCapable) o).jdoNewObjectIdInstance();
((PersistenceCapable)o).jdoCopyKeyFieldsToObjectId(id);
kpm.currentTransaction().begin();
try {
Object trio = kpm.getObjectById(id, true);
kpm.deletePersistent(trio);
kpm.flush(); //apply deletes on the datastore
} catch (ObjectNotFoundException oe) {
System.out.println("First time!");
kpm.makePersistent(o);
kpm.currentTransaction().commit();

Answer 1

If this is a question, the extension you have is only a directive to
mappingtool to create cascade foreign keys. However, at runtime Kodo
will rely upon the foreign key definitions in the schema. You should
verify that the foreign key exists as you like in the schema. If you
want to have child relationships to be deleted, you should use the
dependent and element-dependent extensions.
Ahmet Bulut wrote:
Assume that I have two classes that I'd like to persist: MyObject and
InternalObject. MyObject has an InternalObject field. That is, MyObject is
the parent, InternalObject is the child in this one-to-one relationship.
Steps involved:
1) Enable ForeignKeyConstraints property in kodo.properties. That is add
the line,
kodo.jdbc.ForeignKeyConstraints=true
2) In package.jdo, add the following kodo extensions for MyObject's
InternalObject field mapping, i.e., io in my case.
<field name="io" default-fetch-group="false">
<extension vendor-name="kodo" key="jdbc-delete-action"
value="cascade"/>
<extension vendor-name="kodo" key="dependent" value="true"/>
</field>
The reasons that we have done these steps: we'd like kodo to properly
re-order the sql statements if necessary in order not to violate
parent/child dependencies during insertion, and also force cascading
deletes in case we delete the parent object.
Now comes the bulk of the algorithm.
String sKey // key of the object to insert
String sValue //value of the object to insert
MyObject o = new MyObject(sKey, sValue);
InternalObject io = new InternalObject(sKey,sValue); //using same values :)
o.setInternalObject(io); //parent-child relation
Object id = ((PersistenceCapable) o).jdoNewObjectIdInstance();
((PersistenceCapable)o).jdoCopyKeyFieldsToObjectId(id);
kpm.currentTransaction().begin();
try {
Object trio = kpm.getObjectById(id, true);
kpm.deletePersistent(trio);
kpm.flush(); //apply deletes on the datastore
} catch (ObjectNotFoundException oe) {
System.out.println("First time!");
kpm.makePersistent(o);
kpm.currentTransaction().commit();
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com