RE: Core Data Fetching Limitations?
RE: Core Data Fetching Limitations?
- Subject: RE: Core Data Fetching Limitations?
- From: Ulai Beekam <email@hidden>
- Date: Tue, 23 Jun 2009 21:30:55 +0000
- Importance: Normal
Sure. It is not mentioned in the "Core Data Programming Guide". However it is mentioned in "Predicate Programming Guide".
Take a look at the section called "Constraints and Limitations" (second item in the list) on this page:
http://developer.apple.com/documentation/Cocoa/Conceptual/Predicates/Articles/pBasics.html#//apple_ref/doc/uid/TP40001792
To tell you the truth, I think your question is very good. Because in the meantime, I actually tried combining two "IN"s together (to be more precise, I combined both of them in an NSCompoundPredicate) and it seemed to work fine, even with SQLite!
I therefore ask: Was there any particular reason for why you asked me? I am starting to suspect that there was a good reason for it :) Please feel free to share with me everything you know about this topic.
----------------------------------------
> Date: Tue, 23 Jun 2009 12:17:24 -0700
> Subject: Re: Core Data Fetching Limitations?
> From: email@hidden
> To: email@hidden
>
> Ulai,
>
> Can you point me to the documentation that gives the "only one IN" per
> query limitation of SQLite?
>
> Thanks,
> Barry
>
> 2009/6/21 Ulai Beekam :
>>
>> (Sorry, the previous post was not sent with plaintext)
>>
>> Please draw up the following model on a piece of paper:
>>
>> We have three entities: Department, Employee, and EmployeeCar. Each of them has the 'name' attribute.
>>
>> Department has the to-many 'employees' relationship to Employee. Its inverse is, naturally, the to-one 'department' relationship in Employee.
>>
>> Employee has a to-one 'employeeCar' relationship to EmployeeCar. Its inverse is the to-many 'employees' relationship in EmployeeCar. This reflects the reality that a single car can be assigned to more than one employee, but a given employee does only have one car assigned to him.
>>
>>
>> NOW HERE IS THE QUESTION: How can I make Core Data: **** fetch all departments that have an employee whose name starts with 'Jo' and whose assigned car has the name of 'Volvo' ****
>>
>>
>>
>> Can Core Data even make such fetches? Can it be done without ALL,ANY? I ask because I might want to combine many such conditions, making it impossible to do with the SQLite storage option. Maybe I can just simply forget the SQLite storage for this? What are the alternatives? Am I doomed to work with the other slower storages?
>>
>> And note that I do indeed have to have it inside a single predicate because I have an NSArrayController of Department objects, and after having made the correct predicate (for which I need your help) I plan to set the array controller's fetch predicate to that predicate.
>>
>> Thanks, U.
>> _________________________________________________________________
>> Invite your mail contacts to join your friends list with Windows Live Spaces. It's easy!
>> http://spaces.live.com/spacesapi.aspx?wx_action=create&wx_url=/friends.aspx&mkt=en-us_______________________________________________
>>
>> Cocoa-dev mailing list (email@hidden)
>>
>> 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:
>>
>> This email sent to email@hidden
>>
_________________________________________________________________
Drag n’ drop—Get easy photo sharing with Windows Live™ Photos.
http://www.microsoft.com/windows/windowslive/products/photos.aspx_______________________________________________
Cocoa-dev mailing list (email@hidden)
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:
This email sent to email@hidden