Question

class Article
  has_many :comments
end

class Comment
  belongs_to :article
end

I’d like to be able to determine how many total comments exist for certain articles. For example: Article #20, #21 and #22 have a total of X comments between them.

Any pointers would be great!

Answer 1

I suggest this:

Comment.where(:article_id => [20, 21, 22]).count

Doing the counting etc. in the database and all in one query (which ActiveRecord will, in this case) is about as efficient as possible.