> It''s been a long time since I've done this (years, Cayenne 1.2 with > outer join support), but I seem to recall being about to do this with > a ExpressionFactory.matchExp(path, null).
Well, wouldn’t you know — that actually worked! Although the SQL it generates is a little wonky. It attempts to join on a destination key of null (which of course never exists, so it always returns empty relationships). Haven’t seen it before but perhaps it’s perfectly legal. > Like Andrus said, you might need to add a "+" in there to force an outer join. > > Sorry I can't be of more help. > > It would be great if you submitted an expression type that supported > this trivially. Let’s hope it ends up that way :). - hugi > On Fri, Jul 24, 2015 at 12:56 PM, Hugi Thordarson <h...@karlmenn.is> wrote: >> Indeed :). I’ve been looking at the Expression classes for a while now and >> they look a little daunting. Any recommendations on where to start? Is there >> a developer guide or an annotated example implementation somewhere? >> >> - hugi >> >> >> >>> On 24. júl. 2015, at 15:59, Andrus Adamchik <and...@objectstyle.org> wrote: >>> >>> Classic open source - "scratch your own itch" :) >>> >>> >>>> On Jul 24, 2015, at 6:54 PM, Hugi Thordarson <h...@karlmenn.is> wrote: >>>> >>>> Thanks Andrus, we’ll revert to EJBQL for now. >>>> >>>> Looks like an excellent opportunity to try and implement my first >>>> Expression class :) >>>> >>>> - hugi >>>> >>>> >>>> >>>>> On 24. júl. 2015, at 15:36, Andrus Adamchik <and...@objectstyle.org> >>>>> wrote: >>>>> >>>>> We should add it. For now OUTER JOIN should do the trick: >>>>> >>>>> "a.paintingArray+ = null" >>>>> >>>>> Also EJBQL syntax supports "IS [NOT] EMPTY" : >>>>> >>>>> "SELECT a FROM Artist a WHERE a.paintingArray IS EMPTY" >>>>> >>>>> Andrus >>>>> >>>>>> On Jul 24, 2015, at 5:51 PM, Hugi Thordarson <h...@karlmenn.is> wrote: >>>>>> >>>>>> Hi all. >>>>>> Does Cayenne have an Expression class that allows searching for objects >>>>>> with an empty to-many relationships? If not, any pointers towards a >>>>>> sensible approach? >>>>>> >>>>>> Cheers, >>>>>> - hugi >>>>>> >>>>>> // Hugi Thordarson >>>>>> // http://www.loftfar.is/ <http://www.loftfar.is/> >>>>>> // s. 895-6688 >>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >>
