Hello,
I am using the ODMG API.
i don't know whether this behaviour is to be expected:
I am mapping a child class to it's parent class via multiple joined tables.
When I retrive objects of the parent class from the Database, some of the
returned objects should be members of a child class.
But if i ask for the objects of the parent class, I only get them as
instances of the parent class.
In the spy.log - File I can see that only parent objects are retrieved.
What can I do to get the "real" objects?
The repository:
<class-descriptor class="test.Point" table="point">
<field-descriptor id="1" name="id" column="id"
jdbc-type="INTEGER"
primarykey="true" autoincrement="true"
access="anonymous"/>
<field-descriptor id="2" name="region" column="region"
jdbc-type="VARCHAR"/>
</class-descriptor>
<class-descriptor class="test.NamedPoint" table="namedpoint">
<field-descriptor id="1" name="id" column="id"
jdbc-type="INTEGER"
primarykey="true" autoincrement="true"
access="anonymous"/>
<field-descriptor id="2" name="name" column="name"
jdbc-type="VARCHAR"/>
<reference-descriptor name="super" class-ref="test.Point">
<foreignkey field-ref="id" /> </reference-descriptor>
</class-descriptor>
the table definitions:
CREATE TABLE point (id INT PRIMARY KEY, region VARCHAR (20)) ;
CREATE TABLE namedpoint (id INT PRIMARY KEY,name VARCHAR (20)) ;
the main - Method (Class definitions are as expected from the repository):
public static void main(String[] args) {
// Open Database
Implementation theOdmg = OJB.getInstance();
Database theDb = theOdmg.newDatabase();
try {
theDb.open("default", Database.OPEN_READ_WRITE);
} catch (ODMGException ex) {
ex.printStackTrace();
}
//Create a NamedPoint
Transaction tx = theOdmg.newTransaction();
tx.begin();
NamedPoint np = new NamedPoint();
np.setRegion("region");
np.setName("test");
tx.lock(np, Transaction.WRITE);
tx.commit();
//get Point
tx = theOdmg.newTransaction();
tx.begin();
OQLQuery query = theOdmg.newOQLQuery();
DList pointList = null;
try {
String queryString =
"select all from " + Point.class.getName() + "
where region =\"region\"";
query.create(queryString);
pointList = (DList) query.execute();
java.util.Iterator iter = pointList.iterator();
while (iter.hasNext()) {
Point point = (Point) iter.next();
if (point instanceof NamedPoint) {
System.out.println("Named Point!");
} else {
System.out.println("No Named Point!");
}
}
} catch (QueryInvalidException ex) {
ex.printStackTrace();
} catch (QueryException ex) {
ex.printStackTrace();
}
}
the text on the Screen:
No Named Point!
thanks,
Birgitta
