Red Hat Web Application Framework 6.1 Instrukcja Użytkownika Pobierz pdf (Strona 109)

Chapter 9. Persistence Tutorial 95

System.out.println(email + ": " + membershipDate);

}

9.8.2.3. Updating Link Attributes

The DataAssociationCursor.getLink() method can be used to fetch the DataObject that rep-

resents a link. This DataObject can then be used to modify the link and persist the results.

// Put the current session in a variable for convenience.

Session ssn = SessionManager.getSession();

// Get a group.

DataObject group = ssn.retrieve(new OID("Group", ...));

// Get the members association.

DataAssociation members = (DataAssociation) group.get("members");

// Iterate over the members of the group and modify each link.

DataAssociationCursor cursor = members.getDataAssociationCursor();

while (cursor.next()) {

// Fetch the link object for the current row.

DataObject link = cursor.getLink();

// Get the membership date from the link data object.

java.util.Date oldDate = (java.util.Date) \

link.get("membershipDate");

// Incrememnt the membership date by 1 millisecond.

java.util.Date newDate = new \

java.util.Date(oldDate.getTime() + 1);

// Set the new date

link.set("membershipDate", newDate);

}

// Persist all the changed links.

group.save();

Note

Only group.save() is called to persist the changes. Changes to the links are automatically persisted

when the parent object is saved.

9.8.2.4. Filtering and Ordering based on Link Attributes

To access the values of a link attribute when ﬁltering or setting the order of a data association, simply

put the special link preﬁx in front of the link attribute name.

// Put the current session in a variable for convenience.

Session ssn = SessionManager.getSession();

// Get a group.

DataObject group = ssn.retrieve(new OID("Group", ...));

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Red Hat Web Application Framework 6.1 Instrukcja Użytkownika Strona 109