Re: Predicates with object identity values
Re: Predicates with object identity values
- Subject: Re: Predicates with object identity values
- From: Aurélien Hugelé <email@hidden>
- Date: Fri, 25 May 2007 06:09:58 +0200
Glen, there is a small confusion in your explanation:
A Department object has many Employee objects
and
here is a relation Department -> Employee (employee)
The convention is to use ->> (double arrow) to indicate a to many
relationship, and to use plurals (employeeS).
If you have a to one relationship Department -> Employee (employee),
yes your predicate is correct and your FetchRequest is valid.
But if you have a to many relationship Department ->> Employee
(employees)
you'll have to use something like "ANY employees == %@,myEmployee" //
not actually tested
Aurélien
On 25 mai 07, at 02:41, Glen Low wrote:
Hi All
In Core Data, specifically predicate programming, is it possible to
create a NSPredicate to search on an object identity value (as
opposed to a string, number or bool value)?
For example, suppose
A Department object has many Employee objects. There is a relation
Department -> Employee (employee) but no inverse relation Employee -
> Department.
Suppose I have an Employee object called myEmployee and want to
search for its Department, can I use the following fetch request?
NSFetchRequest* request = [[NSFetchRequest alloc] init];
[request setEntity: departmentEntity];
[request setPredicate: [NSPredicate predicateWithFormat: @"employee
= %@", myEmployee]]; // using myEmployee as an object identity
If not, I'd probably have to assign each object a unique,
persistent ID, which is a bit of a pain... or are they any other
solutions?
Cheers, Glen Low
---
pixelglow software | simply brilliant stuff
www.pixelglow.com
aim: pixglen
_______________________________________________
Cocoa-dev mailing list (email@hidden)
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:
40gumitech.com
This email sent to email@hidden
_______________________________________________
Cocoa-dev mailing list (email@hidden)
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:
This email sent to email@hidden