Should includes with general association name work?

rubyonrails-core
#1

Hi, I'm wondering if this is an arel bug or should be a new feature.

I've got a model with the following:

     has_many :recommendations, :class_name => "Referral",
:foreign_key => :candidate_id
    scope :recommended_to, lambda {|er|
joins(:recommendations).where(:referrals => {:employer_representative
=> er})}

This works and generates the right inner join.

puts User.recommended_to(er).to_sql
users" INNER JOIN "referrals" ON "referrals"."candidate_id" =
"users"."id" WHERE ("referrals"."employer_representative" = '6')

But if I change joins to includes in the scope, I get:
puts User.recommended_to(er).to_sql
SELECT "users".* FROM "users" WHERE
("referrals"."employer_representative" = '6')

Which won't work since it needs the join.

I know that the old :include option only generated a join clause if
there was also a condition which required it, and since the includes
method doesn't know that it kind of makes sense. I also tried
chaining the includes after the where in hopes that then include WOULD
know, but it didn't make a difference.

Is there, or should there, be a way in such a case to force includes
to generate the join as well as instantiating the associated records?

#2

This looks like a bug to me. You should try a few things:

* Can you repro on master?
* What about doing where('referrals.employer_representative' => ...) -
does that make a difference?
* Try doing the query manually (i.e. Users.includes(..).where(...)) - I
doubt the scope is the problem but good to rule things out.

(BTW the bug is probably in ActiveRecord::Relation, not arel. Also,
specifying the query in a different order won't make a difference since
the query will only be built when it's needed, not incrementally.)

Cheers