Actually there is a trick involved in naming columns from the joined
tables. So you'd still call 'addPrefetch', but also prefix each joined
column with a DB relationship name. E.g.:
#result('granteeId' 'String' 'myRel.granteeId')
(Note to self - document this under "Advanced SQLTemplate")
Andrus
On Aug 25, 2008, at 9:58 PM, Mike Kienenberger wrote:
I'm not an expert on prefetching.
However, my guess is that you need to use addPrefetch() and let the
framework do the right thing rather than trying to put it into your
sql-template.
On 8/25/08, Michael Shea <[EMAIL PROTECTED]> wrote:
Hi,
I am attempting to use a SQLTemplate to execute a query and prefetch
relationships. I have been unable, so far, to get any relationships
that are
one-to-many to be prefetched. Is there any further documentation
about
prefetching dependencies with SQLTemplate? So far, all I have seen
is this:
http://cayenne.apache.org/doc/prefetching.html
This basically just indicates that SQLTemplate uses JOINT semantics
to
prefetch, which makes sense. Presumably, the query must manually
retrieve
all the desired relationships, and I should call
template.addPrefetch(...)
for every relationship I want retrieved?
How should I retrieve the actual properties of the relationship
objects? So
far, I have been using:
select ...
#result('granteeId' 'String' )
...
where granteeId is a property of an object related to the root
object of
the query.
However, I get back errors like this:
org.apache.cayenne.CayenneRuntimeException: [v.2.0.4
October 8 2007] Null value for 'granteeId'. Snapshot:
org
.apache
.cayenne
[EMAIL PROTECTED]:70f1774a:
11bfb2de554:-8000,
granteeId=null, permissionType=null, isGrantable=null},
version=-9223372036854775793,
replaces=-9223372036854775808]. Prefix: null
at
org
.apache
.cayenne.access.ObjectResolver.createObjectId(ObjectResolver.java:
278)
...
When I run the query myself, manually, I can see that the value of
granteeId returned by the query isn't null.
I have also tried calling template.setFetchingDataRows( false ) and
then
calling context.objectsFromDataRows() on the result of executing
the query,
but so far that has just generated me one object per datarow (so if
a root
object has 4 related dependent objects, I end up getting back 4
distinct
root objects, rather than 1 root with 4 objects in the appropriate
relationship).
Any suggestions? If this is unclear, please let me know and I will
try to
clarify =)
Oh, I am using version 2.0.4 of Cayenne.
Thanks!
Mike Shea.
