Hi Farrukh, I'm no expert on these matters but unless I have a very simple and straightforward plan of inheritance that would be immediately obvious to someone else joining the project, I've avoiding using EOF inheritance. I've dabbled with a number of options depending on the exact circumstances and most importantly, what has the *correct real-life semantic*.
For instance, I've used enums to represent behaviours and have linked these to behaviour classes - the enterprise objects can simply call its registered behaviour object.method - I'm basing this on posts to the list from Ramsey. In other situations, I've simply used java interfaces and implement these within separate entities perhaps factoring out common functionality into a helper class. For your case, I'm finding it difficult to imagine why two entities (IS-A) have such different relationship requirements. If you really need to do this and want to use EOF inheritance, then perhaps you can have two trees of inheritance. The first tree would have Entity X as root. These entities would defer handling of relationships to one of two entities that provide the appropriate relationship behaviour - to-one or to-many. Good luck, Mark On 6 November 2010 11:39, Farrukh Ijaz <[email protected]> wrote: > Hi EOF-ologists, > > I've a modelling issue and need to know what could be the suitable fix (or > tweak) to fulfil the requirement. > > Below is the existing EO Model. > > > I've two entities (Entity A and Entity B) extending Abstract Entity X but > these entities have their own tables (no single table inheritance). I need to > design Entity D and Entity E where Entity D has a toMany relationship with > Entity E and Entity E needs to have a toOne relationship with Entity A, > Entity B, Entity C and Entity D. > > 1. One way can be for Entity E to have four different relationships such as > toEntityA, toEntityB, toEntityC and toEntityD. (This is _not_ desirable) > 2. The other way mentioned in the lower diagram where Entity A, Entity B, > Entity C and Entity D extend Abstract Entity X and Entity E will have toOne > relationship with Abstract Entity X. (This is _desirable_). > > > What would be the easiest way to model such relationship? I'm _not_ > relationship expert so may be the way I assumed the model (second diagram) > can be wrong or practically impossible? > Also note that I cannot make Entity C and Entity D to extend Abstract Entity > X due to some design constraints therefore I think to introduce Abstract > Entity Alpha. > > Thanks, > > Farrukh > > > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Webobjects-dev mailing list ([email protected]) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/webobjects-dev/mark%40wardle.org > > This email sent to [email protected] > -- Dr. Mark Wardle Specialist registrar, Neurology Cardiff, UK _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to [email protected]
