Expression Join

Question

Hello,
I'm having problems doing a join with a TopLink expression.
I am using two tables, and I have the two classes corresponding to these tables.
Also the Java Client file for both Java classes.
In the first Java client (BosetudeClient.java) I have this expression :
     ExpressionBuilder bose = new ExpressionBuilder();
     Expression exp = bose.get("betEorIs").like("1318");
     Vector objects = session.readAllObjects(jsftoplink.model.Bosetude.class,exp);
     return objects;
It returns me in a datatable the correct rows according to this expression.
Now, I want to use a join (and an expression) that links the primary key of a table and the foreign key of the second table.
Do I have to code in the BosetudeClient.java or in the second Client.java file?
How can I call multiple classes in the session.readAllObjects()?
Thank you.

Answer 1

If you have a foreign key between the two, then you should probably have a OneToOneMapping between the two. This way when you read the Bosetude class, you can access its' relationship to the other class.
To optimize the query, you can use fetch joining (addJoinedAttribute()) or batch reading (addBatchReadAttribute()) on the query (ReadAllQuery).
You could also use a ReportQuery to read both objects if you did not wish to relate them.
-- James : http://www.eclipselink.org