On Jul 22, 2010, at 5:00 AM, Paul Hoadley wrote: > Hello, > > I know this topic comes up on the list from time to time, but I just need a > quick sanity check.
Nope, not sane. :-) > I have two entities, A and B. For every A, there is a corresponding B. For > some subset of all Bs, each has a corresponding A. Currently I have modelled > this with a single relationship from A to B, so that's a mandatory to-one > relationship. (Alternatively, I could have modelled it with an optional > to-one relationship from B to A.) > > At different times, I need to traverse this relationship in both directions. > For any A, A.b() will give me the related B. But for the reverse direction, > say I have a B and I want its A (if it has one), I have a custom method B.a() > which does a fetch for the A such that A.b() is the B of interest. > Sometimes, though, I just want to know if there is an A for a particular B, > or whether it's null, and in this setting, the fetch is expensive. > > Here's where I need the sanity check: is there a way, given the constraints > above, to model an inverse to-one relationship from B to A such that it > appears as the inverse to EOF? That is, such that calling, say, > A.addObjectToBothSidesOfRelationshipWithKey(B, "b") does both A.setB(B) and > B.setA(A)? I'm assuming there's not, as I certainly can't beat the model > into doing it. I can work around it by doing the right thing at creation > time for every A, I just wanted to know if I was missing something where EOF > (or Wonder) would handle this automagically. How are you modeling these relationships? Chuck -- Chuck Hill Senior Consultant / VP Development Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems. http://www.global-village.net/products/practical_webobjects
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