Re: CoreData modeling a mutable attribute set for an entity
Re: CoreData modeling a mutable attribute set for an entity
- Subject: Re: CoreData modeling a mutable attribute set for an entity
- From: Jesse Grosjean <email@hidden>
- Date: Tue, 3 Jan 2006 13:57:26 -0500
I'm not sure, but it's possible that Core Data inheritance isn't
the right choice. I haven't used it, but I remember that under EOF,
use of inheritance was discouraged, though I don't know the
reasoning behind that.
Perhaps you should pick a single attribute type to use for your
concrete attribute, and then create transient attributes to
translate it into other values. Do you intend for @"2" to be
different from 2.0 for some reason? Can't you just use strings for
both key and value?
Thanks, I hadn't thought of this and it might just be the answer. At
the application level I want the attributes typed, but I guess they
don't need to be typed at the CoreData level. Is their anything
essential that I'll miss when I bypass the CoreData type system in
this way? Here's the things that I can think of, please let me know
if there is some essential thing that CoreData's type system does
that I'm missing:
- I'll now be responsible for turning object values (like dates) into
query-able strings.
- I'll have to type-check the values before turning them into strings
(so that a date doesn't end up in a column that's typed for strings)
- It looks like I'll have to only pass string query terms to
predicateWithFormat:
I'm not sure what exactly your needs are, but I'm guessing that
you're setting yourself for some significant headaches on this
path :-/
My specific needs are to allow users of my notebook application
(google "Mori notebook" ) to add their own custom columns. This
allows them to associate new attributes with their notebook entries.
OmniOutliner has a similar "add column" feature that you might be
more familiar with.
Thanks,
Jesse
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