Sorting by a virtual attribute in Rails 3

Question

BACKGROUND: I have a set of Posts that can be voted on. I\'d like to sort Posts according to their \"vote score\" which is determined by the following equation:

Answer 1

1. You shouldn't use sort! if you are going to assign to the same variable (it is wrong in this case), you should change the sort to:

   @posts.sort!{|a, b| vote_score(b) <=> vote_score(a) }
   

2. It looks like you are counting the votes for Post each time you call another Post which is hitting the database quite a bit and probably the source of the toll on your load times, you can use a counter_cache to count each time a vote is made and store that in the posts table. This will make it so you only do one db query to load from the posts table.

http://guides.rubyonrails.org/association_basics.html