Re: CoreData: Using to-may relationships in fetch request predicates
Re: CoreData: Using to-may relationships in fetch request predicates
- Subject: Re: CoreData: Using to-may relationships in fetch request predicates
- From: Jerry Krinock <email@hidden>
- Date: Fri, 21 Aug 2009 09:25:34 -0700
Everything I.S. said is true, and as far as I know you're out of luck.
You might want to log into Bug Reporter and "second" my bug 6857142:
05-May-2009 07:05 AM
Jerry Krinock: Summary: Core Data's fetches cannot handle arbitrary
predicates produced by NSPredicateEditor
Steps to Reproduce:
1. Begin designing a data-based application with the intention of
using the latest and greatest technologies Apple has provided.
2. Manage data using Core Data.
3. To maximize the application's search capabilities and reduce the
amount of code necessary to write, add NSPredicateEditor to user
interface.
4. Write code to implement the search. To allow scaling up to large
data sets without bumping into user RAM limitations, instead of
fetching all objects from the store and filtering using -[NSArray
filteredArrayWithPredicate:], create an NSFetchRequest and -
setPredicate to the objectValue of NSPredicateEditor.
Expected Results:
Everything should be cool.
Actual Results:
From "Core Data Programming Guide", "The Core Data SQL store supports
only one to-many operation per query; therefore in any predicate sent
to the SQL store, there may be only one operator (and one instance of
that operator) from ALL, ANY, and IN." Since NSPredicateEditor can
produce predicates with more than one ALL, ANY or IN operator, this
app is not going to work.
Notes: I have used sqlite3 directly myself and don't recall any
limitation on the number of ALL, ANY or IN clauses. So maybe Apple
could fix this.
https://bugreport.apple.com/cgi-bin/WebObjects/RadarWeb.woa/wa/signIn
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