Use of abstract entities with relationships
Use of abstract entities with relationships
- Subject: Use of abstract entities with relationships
- From: Michael Rutt <email@hidden>
- Date: Wed, 26 Apr 2006 20:25:49 -0400
I'm working on my first Core Data application and am running into
some issues with abstract entities and relationships. I have been
Googling and searching these lists for two days and have not been
able to find a clear answer to my problem, so I'm hoping someone can
give me a hand with this! Basically, I'm trying to code to the base
(generic) entities rather than the specific entities that inherit
from them.
Example: I have an abstract entity called account. That account has
two relationships, one is parent (which is one-to-one with Account)
and one is children (which is one-to-many with Account). Basically
this allows for a file-system like structure. Then I specialize the
numerous account types available as entities with Account as their
parent. So I might have a SalesAccount entity and a PurchaseAccount
entity. If I create a SalesAccount entity and want to give it a
child of PurchaseAccount, I get an error saying:
Unacceptable type of value for to-one relationship: property =
"parent"; desired type = Account; given type = SalesAccount; ... etc.
So my question is, are relationships to abstract entities even
possible? And if so, how does one go about creating a specialized
entity and assigning it to the relationship? If there isn't an
"easy" way, I was considering creating some fetched requests to get
the children relationships...
Maybe the answer is as simple as me not fully understanding the Core
Data modeling concept and how it should work. I was just trying to
keep it generic (like classes) vs. creating relationships between all
the non-abstract account types...
Any input would be GREATLY appreciated!
Thanks
Mike
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