Thanks for all your help, Jakob - I'll give it a try!
Gary
--- Jakob Braeuchi <[EMAIL PROTECTED]> wrote:
> hi gary,
>
> i propose you define a m:n mapping between Test and
> Test_Panel with
> Panel_Test_Table as intermediate table.
>
> i'm not sure about the pk Panel_Test_Table. in our
> examples the pk is the
> combined pk of the linked tables. afaik it's not
> possible to define a special pk
> for the intermediate table, but you could probably
> use an autoincrement feature
> of your dbms.
>
> the other point is that Test ans Test_Panel are
> mapped to the same table. ojb
> uses the column ojbConcreteClass to distiguish the
> class in the table. this
> column is automatically added in QueryFactory and
> it's also used by
> RowReaderDefaultImpl to get the class to be
> instantiated.
>
> protected ClassDescriptor selectClassDescriptor(Map
> row) throws
> PersistenceBrokerException
> {
> // check if there is an attribute which
> tells us which concrete class
> is to be instantiated
> FieldDescriptor concreteClassFD =
> m_cld.getOjbConcreteClassField();
>
> if (concreteClassFD == null)
> return m_cld;
> else
> {
> ....
>
> you'll have to implement your own row-reader using
> the column 'category' to
> decide which class to use.
>
> hth
>
> jakob
>
> Gary wrote:
>
> > Jakob:
> >
> >
> >>>Thanks for your quick reply.
> >
> >
> > --- Jakob Braeuchi <[EMAIL PROTECTED]> wrote:
> >
> >>hi gary,
> >>
> >>imo the table Panel_Test_Table is a link table to
> >>connect rows in Test_table, is
> >>that correct ?
> >>
> >>>Yes
> >>
> >>Test_table
> >>test_key / category
> >>
> >>55 / PA
> >>10 / TE
> >>15 / TE
> >>66 / PA
> >>
> >>Panel_Test_Table
> >>panel_test_key / panel_key / test_key
> >>
> >>1 / 55 / 10
> >>2 / 55 / 15
> >>3 / 66 / 10
> >>
> >>a test can be connected to multiple panels ?
> >>
> >>>Yes
> >>
> >>is it a m:n relationship between Test_table rows ?
> >>
> >>>Yes, if I understand the question, when the
> >
> > category >> is "PA"
> >
> >>what's the meaning of the panel_test_key ?
> >>
> >>>No meaning, just a unique ID for the row.
> >>
> >>jakob
> >>
> >>
> >>Gary wrote:
> >>
> >>
> >>>I have a, for me, complex OJB problem, and am
> >>
> >>looking
> >>
> >>>for pointers.
> >>>
> >>>I have two classes: a Test, and a PanelOfTests.
> I
> >>>have two tables: Tests_Table, and
> >>
> >>Panel_Test_Table.
> >>
> >>>Here is the pseudocode:
> >>>
> >>>public class Test {
> >>> int testID;
> >>> String category; // can be "TE" for test, "PA"
> >>
> >>for
> >>
> >>>panel
> >>>}
> >>>
> >>>public class PanelOfTests extends Test {
> >>> Collection tests; // a collection of Test
> objects
> >>>}
> >>>
> >>>table Tests_Table
> >>> test_key, int
> >>> category, varchar
> >>>
> >>>table Panel_Test_Table
> >>> panel_test_key, int
> >>> panel_key, int
> >>> test_key, int
> >>>
> >>>A PanelOfTests then is in fact a Test, one that
> >>
> >>has a
> >>
> >>>category of "PA," and which contains 1-n other
> >>
> >>Tests.
> >>
> >>>To find the tests that a given panel (say, 55)
> >>>contains I get all the rows in Panel_Test_Table
> >>
> >>where
> >>
> >>>panel_key = 55 and instantiate a Test object for
> >>
> >>each
> >>
> >>>of the test_keys.
> >>>
> >>>Any good ideas on how to do this in OJB
> >>
> >>metadata/row
> >>
> >>>readers/? I am unable to change the database
> >>
> >>layout.
> >>
> >>>Thanks, Gary
> >>>
> >>>__________________________________
> >>>Do you Yahoo!?
> >>>Yahoo! Mail - More reliable, more storage, less
> >>
> >>spam
> >>
> >>>http://mail.yahoo.com
> >>>
> >>>
> >>
> >
>
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