Re: Single-table inheritance error
Re: Single-table inheritance error
- Subject: Re: Single-table inheritance error
- From: Chuck Hill <email@hidden>
- Date: Wed, 30 Sep 2009 13:16:49 -0700
Hi Jon,
On Sep 30, 2009, at 1:10 PM, Jon Nolan wrote:
I have something like this modeled in single-table inheritance:
AbstractResource
Resource1
Resource2
...
ResourceN
AbstractResource is marked as abstract and a class attribute named
"resourceType" handles the restricting qualifier.
If I execute this:
NSArray<AbstractResource> resources =
AbstractResource.fetchAllAbstractResources(ec());
I get this:
java.lang.IllegalStateException: Unable to determine subentity of
'AbstractResource' for row: { ...bunch of attributes... }. Check
that the attribute 'resourceType' is marked as a class property in
the EOModel and that the value satisfies some subentity's
restricting qualifier.
The attribute _is_ marked as a class property and the value _does_
satisfy some subentity's restricting qualifier.
Are you sure it is marked as a class property in every single entity?
Is there one entity that has a subtle difference in the modeling of
this?
This is beyond doubt. I read somewhere once that there's a fluky
thing wherein the order of the entities alphabetically within the
model matters. Hence my parent entity begins with "A" and is the
very first entity in my model. Doesn't help.
I don't recall that.
I have had it working for weeks by making AbstractResource non-
abstract and that gets me past the throw but it causes me problems
in other areas (i.e. a fetchRequiredXXX against Resource returns
two copies.) I'm coming back now to do this "the right way" and
make single-table inheritance with an abstract parent work as I
imagine it should.
Adding a unique restricting qualifier to the abstract entity should
avoid the duplicates. I don't recall running into this.
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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