On Mar 11, 2009, at 1:20 PM, Chuck Hill wrote:
On Mar 11, 2009, at 9:46 AM, David Avendasora wrote:
Hi all,
I've run into something that I haven't been able to find documented
anywhere, but does seem to fit with other Cross-Model relationship
issues (http://lists.apple.com/archives/Webobjects-dev/2008/Dec/msg00058.html
).
If you have a cross-model relationship,
Same database or different database?
It is a different database. It happens to reside on the same DB
server, but there's no guarantee that that will be the case long term.
you can't prefetch the relationship when constructing an
EOFetchSpecification. It will simply return null, or an empty
NSArray if it is a to-many relationship.
I think that would be a bug. Prefetching is a separate select so it
should not matter if it is in a different database.
I thought it would do a separate select, but using a join to get only
the related EOs. Otherwise how would it know which records to select?
If it is a cross-DB join, then EOF (or the DB plugin - MSSQL in this
case) would need to add the Server and Database name to the table
names in the SQL such as:
SELECT T2.column1, T2.column2, T3.etc FROM Server1.WO.dbo.table T1,
Server2.GP.dbo.table1 T2 WHERE T1.pkColumn = T2.fkColumn
Subsequent calls to the relationship simply return null or the
empty NSArray.
Which is clearly a bug if they return proper results normally.
Yep. I took out the prefetch path for the cross-model relationship and
now when relationship() is called on one of the fetched EOs a round-
trip to the database is done and I get exactly what I would expect.
Is this the expected behavior?
No to me.
Am I the first to ever prefetch a cross-model relationship?! I would
think that those would be prime candidates for prefetching, especially
if it is a different DB server.
Or is this a case of the Microsoft DB plugin just not handling the
relationship properly?
Dave
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