obj_extract should treat ActiveRecord::Associations::CollectionProxy as an Array

[jrochkind]

Right now it doesn't, so you need to explicitly put to_a into your obj_extract paths, to turn it into an array.

One way to accomplish this would be to treat anything that respond_to?(:to_ary) as an array, rather than hard-coding ActiveRecord::Associations::CollectionProxy. Note that's to_ary not to_a, and thus should work fine, only things that really are meant to be interchangeable with Array should have to_ary.

I think this is a definite improvement... but ti's a backward incompatibility, since anything doing an explicit to_a will break.

Could be done with an obj_extract2 or something to be backwards compat. I dunno.