Re: NSPredicate for a ANY match based on two properties at once
Re: NSPredicate for a ANY match based on two properties at once
- Subject: Re: NSPredicate for a ANY match based on two properties at once
- From: "Jim Turner" <email@hidden>
- Date: Fri, 20 Jun 2008 13:06:57 -0500
On Fri, Jun 20, 2008 at 10:56 AM, Jesse Grosjean
<email@hidden> wrote:
> I'm having a hard time figuring out how to construct a query. The objects
> involved are:
>
> Entry
> - has many tags
>
> Tag
> - name (string)
> - value (string)
>
> I want to construct searches such as:
>
> - find all entries that have a the tag named "priority" with the
> value "1".
>
> I can use [NSPredicate predicateWithFormat:@"ANY tags.name = %@", tag.name]
> to find all entries that have a particular tag... but I don't know how to
> also figure in the value.
>
> I don't need this predicate to work with a database, these queries are all
> just being run in memory, with my own custom model objects (not using Core
> Data). If there is no way to do this in a format string, is there some way
> to do it by directly constructing a predicate object?
>
> Thanks,
> Jesse
> _______________________________________________
>
Jesse,
I'm thinking NSCompoundPredicate is what you're looking for. You
should be able to do something like this:
NSPredicate *tagPredicate = [NSPredicate predicateWithFormat:@"ANY
tags.name = %@", tag.name];
NSPredicate *valuePredicate = [NSPredicate predicateWithFormat:@"ANY
tags.value = %@", tag.value];
NSPredicate *combinedPredicate = [NSComparisonPredicate
andPredicateWithSubpredicates:[NSArray arrayWithObjects:tagPredicate,
valuePredicate,nil]];
If the "simple" predicateWithFormat: predicates don't work,
NSComparisonPredicates will definitely do what you need (I've never
tried creating a compound predicate with predicateWithFormat:
predicates)
--
Jim
http://nukethemfromorbit.com
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