I agree with the query vs. relationship comparison. Unfortunately the
mapping solution will correspond to a mapped query, vs. query created
in the code.
It is only easy to implement if we allow the list to go unordered on
changes of its objects. Which I think is ok, as I mentioned earlier.
Andrus
On Mar 4, 2010, at 2:55 AM, Andrey Razumovsky wrote:
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 <[email protected]>
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
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Aristedes Maniatis
GPG fingerprint CBFB 84B4 738D 4E87 5E5C 5EFA EF6A 7D2E 3E49 102A
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Andrey
