Make members of a has_many share a reference to their belongs_to


#1

Hi all,

I have a model (Foo) with a has_many association to another model
(Bar). Each Bar backreferences Foo, and calls a method on Foo that is
expensive to call the first time per-instance (Foo#pricey). If all the
instances of Bar referenced the same instance of Foo, the cost of
calling Foo#pricey would only have to be paid once. Alas, this is not
so:

foo = Foo.find :first
foo.object_id
=> 70169390687560

foo.bars[0].foo.object_id
=> 70169406714940

foo.bars[1].foo.object_id
=> 70169407605180

I haven’t looked into the problem too much, since I thought this was
perhaps a simple, common problem for which solution patterns already
exist. Are there? Alternatively, can you recommend a good starting
point for developing a pattern?

Thanks,
Ian


#2

On 11 Dec 2008, at 03:40, I. E. Smith-Heisters wrote:

foo = Foo.find :first
point for developing a pattern?

There’s certainly not an established solution to this, but there are
various experiments such as
http://github.com/h-lame/parental_control/tree/master

Fred


#3

On Thu, Dec 11, 2008 at 12:59 AM, Frederick C.
removed_email_address@domain.invalid wrote:

instances of Bar referenced the same instance of Foo, the cost of

Cool, thanks Fred. Unfortunately the one relationship he doesn’t
support is belongs_to <-> has_many :frowning: No matter, i solved the problem
the old fashioned way by just optimizing the hell out of it. Which is,
of course, preferable in many ways. Still, that’s some neat code and
could well come in handy in other ways.

Thanks again,
ISH