On Apr 28, 2009, at 7:31 PM, M.Y. Tjoe wrote:
Hi all,
I am currently investigating an interesting problem. Here is the
problem description:
A database table "Person" is represented in EOModel as "Person" with
3 childs "Staff" , "Student", "External". There is type column in
Person to tell if he is staff/student/external.
The problem is that when a "External" object is fetched into a ec,
changed its type to "student" and saved changes,
You cannot, may not, must not change the type of an object. Look at a
Role pattern instead.
Chuck
i.e.
External external = External.fetchExternal(ec, External.ID_KEY,
'12345');
external.setType("student");
external.editingContext().saveChanges();
then in the same ec (or different ec) the now "student" still being
recognized as External somehow.
When you do
Student student = Student.fetchRequiredStudent(ec, Student.ID_KEY,
'12345');
or even
Person student = Person.fetchRequiredPerson(ec, Person.ID_KEY,
'12345');
An databaseContextFailedToFetchObject exception is thrown.
I am thinking the objects graph is now broken because Staff Object
supposed to be vanished from the graph but it didn't.
Any idea??
Regards,
Harvey
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