I’ve done this before with a derived attribute to count to many relationship objects.
https://github.com/nullterminated/ponder/blob/master/ERR2d2w/Sources/er/r2d2w/ERR2d2w.java#L111 I was very green when I wrote that, so it’s sorta crappy. It doesn’t support compound FKs. Despite the comment, count(*) is not really MySQL specific. But it worked for me then. That allowed me to display (and sort) to many relationships as a count of objects in that relationship. Derived counts only update on fetch, so they might be too stale in your case. You could also try a ERXExistsQualifier. That is sorta buggy, but it has worked for me in limited usage. It probably won’t be much help unless you use it in a fetch though. In memory, I suspect it just triggers a fault like anything else. On Feb 3, 2016, at 6:34 PM, OC <[email protected]> wrote: > Hello there, > > I'd bet this must be a WebObjects 101, but I can't see the best answer: is > there an efficient way of checking whether an eo.someRelationship is empty? > > So far I simply check eo.someRelationship.count==0, but that might fire a > fault, which is not exactly efficient if the only need is to know whether the > relationship is empty or not. > > Of course I could rig myself something like “if already fetched in, simply > check array count; if still fault, fetch max one object and see whether > there's any...”, but this looks like a ubiquitous task enough it simply > _must_ be done already (and in a far better way than I would do it myself)? > > Thanks for any advice, > OC > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Webobjects-dev mailing list ([email protected]) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/webobjects-dev/rgurley%40smarthealth.com > > This email sent to [email protected] _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to [email protected]
