Rails eager loading of counts?

Question

Eager loading is nice with the include attribute

Post.find(:all, :include => :author)

I\'m wondering if you can also eager load counts, like

Answer 1

Building off of avaynshtok's answer, the following technique should just make 2 database calls.

# ./app/controllers/posts_controller.rb

def index
  # First load the posts
  @posts = Post.all

  # Then you can load a hash of author counts grouped by post_id
  # Rails 4 version:
  @comment_counts = Comment.group(:post_id).count
  # Rails 3 version:
  # @comment_counts = Comment.count(:group => :post_id)
end

Then in your view

<% @posts.each do |post| %>
  
  post_count: <%= @comment_counts[post.id] %>
<% end %>