Hi Michael! Thanks for the pointer. I did try to use your AggregateUtils with Cayenne 4.0 a while back but it’s not API compatible with 4.0. I was able to get it to work with some changes, but turned out I was creating a new DB connection for each DB function invocation and some other things I didn’t quite like. So I ended up constructing my own utility class that uses EJBQL (still determining how sensible that was).
https://bitbucket.org/loftfar/jambalaya/src/22d799925a2c110b4823b36d335889e2ccfc3d06/src/main/java/jambalaya/CayenneUtils.java?at=master&fileviewer=file-view-default But thanks for CBE! IT’s been one of the most useful resources for me while learning Cayenne. Cheers, - hugi > On 29. feb. 2016, at 18:09, Michael Gentry <[email protected]> wrote: > > PS. I think the code works correctly, but let me know if it doesn't. > > > On Mon, Feb 29, 2016 at 1:09 PM, Michael Gentry <[email protected]> > wrote: > >> Hi Hugi, >> >> I'm not sure if this will work for 4.0 (since earlier you said you are >> using it), but this is what I'd use for 3.1: >> >> >> https://github.com/mrg/cbe/blob/master/FetchingObjects/Aggregates/src/main/java/cbe/fetching/utilities/AggregateUtils.java >> >> If you have A->>B, you'd construct a SelectQuery to fetch B's where toA = >> your A object. Basically, invert your query and count the matches. >> Something like: >> >> SelectQuery selectQuery = new SelectQuery(B.class); >> selectQuery.setQualifier(ExpressionFactory.matchExp("toA", a)); >> int countOfB = AggregateUtils.count(dataContext, selectQuery); >> >> Some other example uses: >> >> >> https://github.com/mrg/cbe/blob/master/FetchingObjects/Aggregates/src/main/java/cbe/fetching/Aggregates.java >> >> mrg >> >> >> On Mon, Feb 29, 2016 at 7:25 AM, Hugi Thordarson <[email protected]> wrote: >> >>> Hi all, >>> >>> Is there any simple way or me to count the number of destination objects >>> of a to-many relationship? (without fetching) If not, is there some way to >>> generate an expression from a relationship, so I can use that expression in >>> my own counting functions? >>> >>> Cheers, >>> - hugi >> >> >>
