ruby on rails - Active Record: Eager load association with parameter -

i have following models:

class rating < activerecord::base   belongs_to :item   belongs_to :user end  class item < activerecord::base   has_many :ratings end 

i want fetch items, , ratings made specific user show current user's rating (if exists!) next each item.

i've tried...

item.includes(:ratings).where('ratings.user_id = ?', user_id) 

...but don't give me items no ratings.

my first thought has_many association argument, , pass argument includes method. doesn't seem exist.

how posts , eager loaded association filtered on parameter without doing n+1 queries or loading entities memory?

step 1

make current_user accessible in model layer (one technique outlined here: https://stackoverflow.com/a/2513456/163203)

step 2

add association condition gets evaluated during run time.

rails 2

class item < activerecord::base   has_many :ratings   has_many :current_user_ratings,             :class_name => "rating",             :conditions => 'ratings.user_id = #{user.current_user.try(:id)}' end 

rails 3.1 , above

class item < activerecord::base   has_many :ratings   has_many :current_user_ratings,             :class_name => "rating",             :conditions => proc { ["ratings.user_id = ?", user.current_user.try(:id)] } end 

step 3

item.includes(:current_user_ratings)