Question

I have a nested forms like:

class House < ActiveRecord::Base
  has_many :rooms
  accepts_nested_attributes_for :rooms
  attr_accessible :rooms_attributes
end

class Room < ActiveRecord::Base 
  has_one :tv
  accepts_nested_attributes_for :tv
  attr_accessible :tv_attributes
end

class Tv 
  belongs_to :user
  attr_accessible :manufacturer
  validates_presence_of :user
end

Now, I want to know for house.id = 1 how many rooms and tvs totally.

In the houses_controller I gave

@houses = House.all

And it s quit simple to get the room count for each house like

<% for house in @houses %>
<%= house.rooms.count %>
<% end -%>

My question is how to get tvs count? I am using this now

<%= house.rooms.map {|room| room.tvs.count}.sum %>

It works, but I am not sure this is good or not. Is there any better way to get it?

Answer 1

I d put a method in the model, trying to avoid code in the views.

class House
  ...
  def tvs
    rooms.inject(0) {|r, t| t + r.tvs }
  end
end

class Room
  ...
  def tvs
    tv ? 1 : 0 # it s has_one association right now
  end
end

Also, if in your controller your are loading all House s objects, and after that you are going to need the Rooms objects, you should load the houses like:

House.find :all, :include => { :rooms => :tv }

This way you are going to do 1 query, with your approach there will be 1 + N_rooms + N_tvs queries

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