-1 on inheritance solution. It is creative, but I imagine that can get
messy very quickly if you have multiple attributes you're trying to do
this with.
As for Luke's solution, I think it is good. But I do wonder if the
interface should be different. Before named scopes it was often
necessary to make custom associations with a :conditions hash. Now
named scopes remove this need and offer a much more flexible solution.
Going back to a custom association here with conditions
(important_tags) seems to go against the grain of scopes to me.
What if it were possible to use the :include option to include named
scopes? It might look like this:
class Product < ActiveRecord::Base
named_scope :visible, :conditions => { :visible => true }
named_scope :available, :conditions => { :available =>
true }, :include => :visible
end
This solves the problem of duplication across named scopes in one
model, but how does this address your problem? Here's where it gets
kind of cool. As you know, the :include option is also used to include
associations. So what if you could nest named scope includes through
associations?
http://gist.github.com/71618
I'm not entirely sure how complex the implementation of this would be,
but I would personally love to see this functionality. I know there
was some discussion of this on Lighthouse some time ago, but I don't
know what became of it and I cannot find it at the moment.
What do you think?
Ryan
On Feb 27, 10:03 am, Duncan Beevers <duncanbeev...@gmail.com> wrote:
> Instead of extracting a specific piece of a named_scope's proxy
> options, I would probably elect to use a more flexible,
> object-oriented solution using inheritance.
>
> http://gist.github.com/71604
>
>
>
> On Fri, Feb 27, 2009 at 9:37 AM, Luke Redpath <ljredp...@gmail.com> wrote:
>
> > In my current project, I have an association model that has various
> > flags available. To keep the implementation of these flags
> > encapsulated, I created named_scopes for each flag and use these
> > scopes for finding and creating.
>
> > This model sits between two others as the join model in a
> > has_many :through association. I actually wanted various
> > has_many :through associations that use the same join model but
> > different scopes. Unfortunately has_many :through doesn't have
> > a :scope option; I could use :conditions to get it working but I've
> > now broken the encapsulation I aimed for when I introduced the named
> > scopes and created unnecessary duplication.
>
> > Hopefully this rather contrived example should make it clear what I'm
> > aiming for.
>
> >http://gist.github.com/71585
>
> > And my initial implementation, currently in use in our app (tries to
> > extend ActiveRecord in the least-intrusive way):
>
> >https://gist.github.com/9d7f86e27014ef5df280
>
> > And now, my attempt to do it properly as a patch to ActiveRecord, with
> > a test.
>
> >http://gist.github.com/71587
>
> > I don't expect this patch to be completely ready for inclusion; there
> > are probably other things to consider such as, do you just want to
> > pull the :conditions from the proxy? Is there anything else to pull
> > in? Could this be written in a better way (probably, my knowledge if
> > the AR internals is slim).
>
> > Any thoughts?
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