On 31 Jul 2009, at 20:24, Nate Wiger wrote:
>
> I've tried to dig thru the docs for delegated properties/etc, but
> can't seem to find the magic incantation in DM. How would I achieve
> this in DM?
Well, what you see here is the result of a major difference in how DM
is architected compared to AR. ActiveRecord creates object by mapping
the result sets directly, but DataMapper is explicit about this in
it's model definitions. This means that you never magically get
a .rank method on a model, even if it's returned by find_by_sql.
find_by_sql is also considered a kind of bastard child in DM and
really isn't compatible with DM's goal of being storage engine agnostic.
If you want to run raw queries with DM, I always use the following
approach:
data = DataMapper.repository.query("select high_score, rank(over
(order by avg_score desc)) as rank from scores")
This will return an array of Struct's which can be iterated over like
the following:
data.each do |line|
line.high_score => 1000
line.rank => 100
end
Imho this also better fits the use case, since cramming non model
properties into an ActiveRecord object has always felt strange to me.
--
Regards,
Dirkjan Bussink
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