Can you make it a derived property? If each Managed object has a reference to the AppDelegate they can just return the comparison of their NSManagedObjectID to the one stored as the user default.
Sandor Szatmari On Aug 15, 2013, at 1:07, Rick Mann <rm...@latencyzero.com> wrote: > > On Aug 14, 2013, at 21:14 , Jerry Krinock <je...@ieee.org> wrote: > >> >> On 2013 Aug 14, at 20:46, Keary Suska <cocoa-...@esoteritech.com> wrote: >> >>> A cleaner approach, IMHO, is to have a holder entity whose sole attribute >>> is a to-one relationship to your other entity. Think of it as a singleton >>> that always exist and maintains the particular managed object. >> >> Indeed Keary's idea is much better, and furthermore you may well already >> such an existing "singleton" entity nearby in that data model, which would >> be the logical place for this to-one relationship. Just add this >> relationship to that existing "singleton" entity. > > On Aug 14, 2013, at 20:46 , Keary Suska <cocoa-...@esoteritech.com> wrote: > >> On Aug 14, 2013, at 6:28 PM, Rick Mann wrote: >> >>> I have a boolean property on an Entity for which only one should ever be >>> true. Is it really bad to implement a custom setter that loads every other >>> instance in the MOC that's true and sets them all to false? My code is >>> actually good about always clearing the current one before setting the new >>> one, but when I'm debugging, I will copy data over from another device, and >>> it can't clear the old one in this case. >> >> I am not sure if it bad, but it sure smells funny ;-) Anyway, the issue may >> be more of the data approach. It is likely that the boolean attribute >> shouldn't belong to the entity at all--i.e. that the attribute is really for >> needed by some other object or process and is not a function of the entity. >> A cleaner approach, IMHO, is to have a holder entity whose sole attribute is >> a to-one relationship to your other entity. Think of it as a singleton that >> always exist and maintains the particular managed object. It also requires >> no code at all to maintain uniqueness--simply assign the relationship. > > Well, I used to store the active instance as a property of my app > (AppDelegate). I'd store the NSManagedObjectID as a user default. > > Unfortunately, I need to be able to sort on the boolean property, and on an > NSFetchedResultsController at that, which won't sort on transient properties. > > Moreover, it seems extraordinarily clumsy to have another entity representing > the app, and to only have a singleton of that. > > -- > Rick > > > > > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/admin.szatmari.net%40gmail.com > > This email sent to admin.szatmari....@gmail.com _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
