ruby - Rails 4 + ActiveRecord: group_by on column from different model -

i have these models:

class user < activerecord::base   has_many :car_votes   has_many :cars end class car < activerecord::base   belongs_to :user   has_many :car_votess end class gamevote < activerecord::base   belongs_to :user   belongs_to :car end 

if want display cars user voted (and group output day when user voted cars):

@voted_cars = @user.car_votes.order('car_votes.created_at desc').group_by { |r| r.created_at.to_date } 

so on output cars user voted grouped days user voted games.

but group output according car_votes.created_at, according cars.created_at. how this?

thank in advance.

if associations allow this(try on rails console):

@c = carvote.first puts @c.car.created_at 

and return value rather error, can do:

@voted_cars = @user.car_votes.order('car_votes.created_at desc').group_by { |r| r.car.created_at.to_date }