Re: Hashcode/ETag for EOs
Re: Hashcode/ETag for EOs
- Subject: Re: Hashcode/ETag for EOs
- From: David Avendasora <email@hidden>
- Date: Wed, 25 May 2011 14:22:17 -0400
On May 25, 2011, at 2:20 PM, David Avendasora wrote:
> I'm guessing this will trigger another round-trip to the db, but what about adding this to your EOGenericRecord subclass:
>
> public int rawHashCode() {
> return EOUtilities.rawRowsMatchingKeyAndValue(editingContext(),
> Identity.ENTITY_NAME,
> ID_KEY,
> primaryKey())
> .lastObject()
> .hashCode();
> }
>
> Obviously, getting the value at a higher level would be better, but does this at least return the same hashCode for every fetch?
>
> Of course, Mike's ERCStamped solution is probably better with less overhead, but what the heck. If I never try to upstage him then it'll never happen, right?!
Well, and the fact that it won't work for EOs with compound PKs... but nobody does that, right?
>
> Dave
>
> On May 25, 2011, at 1:55 PM, Pascal Robert wrote:
>
>> I'm trying to find a way to generate a HTTP ETag for EOs so that caching can be done for REST services. What I want to do is to have the same ETag value for each representation of the EO, so when one of the values change, the ETag value will also change, but if the EO have the same value, it will generate the same ETag as another request got.
>>
>> Problem is: I don't know what to use. I tried with myEO.hashCode() but I did some tests and every time I fetch the EO, the hashcode is different even if the data didn't change. I'm thinking of doing a MD5 digest of part of the EO, but I was wondering if another way exist? I could use a "last modified" date and generate a MD5 of that too, but that date is a better option for the Last-Modified header.
>>
>> --
>> Pascal Robert
>> email@hidden
>>
>> WOWODC 2011 : July 1-2-3, Montreal. wowodc.com
>>
>> AIM/iChat : MacTICanada
>> LinkedIn : http://www.linkedin.com/in/macti
>> Twitter : pascal_robert
>>
>>
>>
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