On Oct 9, 10:24 am, Marnen Laibow-Koser <rails-mailing-l...@andreas-
s.net> wrote:
> MaggotChild wrote:
> > I'm attempting to wrestle an old DB into Rails.
> > This relationship is giving me trouble:
>
> > class Show < AR::Base
> > has_many :segments
> > end
>
> > class Segment < AR::Base
> > belongs_to :show
> > has_one :media #this has no PK/FK relation
> > end
>
> > A Segment is "linked" to Media by Media.name, which is the result of
> > concatenating Segment.name and Segment.part. As I said there are is no
> > PK/PK relation so the actual Segment class looks like this:
>
> > class Segment < AR::Base
> > def media
> > @media ||= Media.find_by_name("#{name}%02d" % part)
> > end
> > end
>
> > This leaves me stuck with a N+1 select problem because I can't say:
> > Segment.all :include => :media
>
> The easiest thing to do would be to modify the media table so as to
> declare the name to be primary key.
Hi Maren,
Modifying the DB isn't possible but I could use the :primary_key
options to has one:
class Segment < AR::Base
belongs_to :show
has_one :media, :primary_key => :media_name
def media_name
"#{name}%02d" % part
end
end
Thanks!
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