Find set that belongs_to another set

Question

I'm sure there's an easy answer for this, but not sure how to word it to search for it.

Given that articles belong to users, if I have a set of three different users, how can I access all of the articles written by any of those users with one query?

Answer 1

Given that user_ids is an array of the user ids:

Article.all(:joins => :users, :conditions => ["users.id in ?", user_ids])

Answer 2

hellvinz's answer helped me work it out :) Since the articles belong to users, that means that they have the user_id attribute on them. I feel pretty silly about this one now xD

user_ids = users.map(&:id)
articles = Article.all :conditions => {:user_id => user_ids}

Saves a join, producing a simpler query.

Thanks!