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From Andrey Razumovsky <razumovsky.and...@gmail.com>
Subject Re: [jira] Updated: (CAY-477) Support for preordered relationships
Date Thu, 04 Mar 2010 07:55:00 GMT
The problem is that explicit query allows orderings, while indirect (via
Artist.getPaintings()) does not (the same can be said about e.g. prefetches
though). So, if I want some array to be sorted (which is quite often) I have
to create queries for to-many orderings. Since I often use reflection-based
invocations, I have to create new methods, like getOrderedPaintings(),
moreover, bother about caching the data. IMO the feature is easy to
implement (most is in the patch, actually) and worth it. Also note that
we've seen several same wishes on the user list

artist.getPaintings(Comparator/Ordering) is fine, but we can't generate that
methods for every relationship, and more generic methods will lose things
like Java Generics advantages.
My vision is that this feature will be used for relationships that are
ordered is same way [by default] in every context - e.g. I want people to be
sorted by name everywhere.

2010/3/4 Aristedes Maniatis <ari@maniatis.org>

> On 4/03/10 8:28 AM, Andrus Adamchik wrote:
>
>> Also here is a reason why I don't find ordering of relationships
>> particularly useful is that things like ordering are context dependent
>> ("context" in a general sense)... The same mapping can be used by
>> different UI frontends with different ordering requirements.
>>
>
> Having a default ordering for ObjEntities defined in the model is what
> Rails does. Any time you fetch that entity, be it directly through a Query
> or via a relation, you get the results back with that ordering.
>
> Personally I don't see the point. Ordering in the database is very useful
> if you are paging the results. Or using a limit. But when following
> relations, neither of those things applies, so you may as well just do it in
> memory once you have the list returned.
>
> Perhaps a simplified notation might be useful though:
>
>  artist.getPaintings(Comparator/Ordering)
>
>
>
> Ari
>
> --
> -------------------------->
> Aristedes Maniatis
> GPG fingerprint CBFB 84B4 738D 4E87 5E5C  5EFA EF6A 7D2E 3E49 102A
>



-- 
Andrey

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