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Re: Avoiding nulls along an EOQualifier's [toMany] keypaths
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Re: Avoiding nulls along an EOQualifier's [toMany] keypaths


  • Subject: Re: Avoiding nulls along an EOQualifier's [toMany] keypaths
  • From: Lachlan Deck <email@hidden>
  • Date: Tue, 14 Nov 2006 10:40:40 +1100

Hi Jerry,

On 13/11/2006, at 11:08 PM, Jerry W. Walker wrote:

Couldn't you override valueForKeyPath in C to do a valueForKeyPath for the D within a try/catch block and catch the exceptions?

That'd be too simple, Jerry ;-) That'll work for this case (where the filtering is in-memory).


It'd be good to know of a way to build a qualifier that'd also work database queries... or better, some kind of sub-EOFetchSpecification that can be used as a result set (like sub-queries in sql) for another fetchSpec within the one fetch.

Cheers.

On Nov 13, 2006, at 2:01 AM, Lachlan Deck wrote:

Hi there,

I have some entities related as follows...
	A -->> B -->> C --> D

...and a qualifier...
new EOKeyValueQualifier( "b.c.d", EOQualifier.QualifierOperatorContains, myD );


...used for a display group to limit the view to those 'a' objects that contain any 'b's that have a relationship to any 'c' that is related to a particular 'd'.

The trouble is that some c's may have a null relationship for d. So, obviously, where relevant NSKeyValueCoding.NullValue's get substituted which cannot resolve the key "d"; and an exception is thrown.

Does anyone have any efficient work-a-rounds?

There's potentially a lot of objects involved - so it'll need to be somewhat efficient.

Thanks in advance...

with regards,
--

Lachlan Deck

--
__ Jerry W. Walker,
WebObjects Developer/Instructor for High Performance Industrial Strength Internet Enabled Systems


    email@hidden
    203 278-4085        office

with regards, --

Lachlan Deck



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References: 
 >Avoiding nulls along an EOQualifier's [toMany] keypaths (From: Lachlan Deck <email@hidden>)
 >Re: Avoiding nulls along an EOQualifier's [toMany] keypaths (From: "Jerry W. Walker" <email@hidden>)

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