Expression Join TopLink

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

You need what is called a parallel expression. The TopLink 9.0.4 documentation describes parallel expressions in section 6.2.1.4.2 of the query building basics chapter.
I am assuming you have a User object mapped to your user table.
User would have fields
id, type, name, group
You could write an expression that looked something like this:
ExpressionBuilder user1 = new ExpressionBuilder();
ExpressionBuilder user2 = new ExpressionBuilder(User.class);
Expression exp = user1.get("group").equal(user2.get("group"));
exp = exp.and(user1.get("type").equal(1));
exp = exp.and(user2.get("name").equal("bar"));