How to join on more three tables in Rails 3 - ruby-on-rails

Question

I would like to join more than three tables in Rails 3.
My code is
class offer < ActiveRecord::Base
belongs_to :user
has_many :usercomments, :dependent => :destroy
has_many :comments, :through => :usercomments, :dependent => :destroy
end
class User < ActiveRecord::Base
has_many :usercomments, :dependent =>:destroy
has_many :comments,:through => :usercomments, :dependent => :destroy
has_many :offers, :dependent => :destroy
end
class Usercomment < ActiveRecord::Base
belongs_to :user
belongs_to :comment
belongs_to :offer
end
class Comment < ActiveRecord::Base
has_one :usercomment, :dependent => :destroy
has_one :offer, :through => :usercomments
has_one :user, :through => :usercomments
end
My schema is:
create_table "offers", :force => true do |t|
t.integer "step_id"
t.integer "user_id"
t.date "offerdate"
end
create_table "users", :force => true do |t|
t.string "firstname", :limit => 100, :default => ""
t.string "lastname", :limit => 100, :default => ""
t.string "email", :limit => 100
end
create_table "usercomments", :force => true do |t|
t.integer "user_id"
t.integer "airoffer_id"
t.integer "comment_id"
t.boolean "shared"
end
create_table "comments", :force => true do |t|
t.string "comment"
t.datetime "created_at"
t.datetime "updated_at"
end
and index.html.erb is:
<% airoffers.each do |airoffer| %>
???
<% end %>
In my html.erb page I would like to find a comment for an offer (offer_id) and an user (user_id).

Answer 1

It looks to me like what you want is:
class User < ActiveRecord::Base
has_many :comments
has_many :offers
end
class Offer < ActiveRecord::Base
has_many :comments
belongs_to :user
end
class Comment < ActiveRecord::Base
belongs_to :user
belongs_to :offer
end
If you want all the Comments that belong to a specific User and a specific Offer, just do Comment.where(:user_id => # :offer_id => #) and pass in the User and Offer you want.
Does this help?

Answer 2

This will give you an array of comments for User#123 en Offer#456
UserComment.find(:all, :conditions => {
:user_id => 123,
:offer_id => 456
}).collect(&:comment)

Answer 3

I would use it this way:
Comment.find(
:all,
:conditions => {
:user_id => 123,
:offer_id => 456
},
:join => :usercomment
)
OR:
Comment.find(
:all,
:conditions => [
"usercomments.user_id = ? AND usercomments.offer_id = ?",
123,
456
],
:join => :usercomment
)
Rails have a lot of beautiful ways to write queries.

Answer 4

Finally, i chose this solution
my code
class offer < ActiveRecord::Base
belongs_to :user
has_many :comments, :dependent => :destroy, :order => "updated_at DESC"
end
class User < ActiveRecord::Base
has_many :comments,:dependent => :destroy
has_many :offers, :dependent => :destroy
end
class Comment < ActiveRecord::Base
has_one :user, :dependent => :destroy
has_one :airoffer, :dependent => :destroy
end
schema
create_table "offers", :force => true do |t|
t.integer "user_id"
t.date "offerdate"
end
create_table "users", :force => true do |t|
t.string "firstname", :limit => 100, :default => ""
t.string "lastname", :limit => 100, :default => ""
t.string "email", :limit => 100
end
create_table "comments", :force => true do |t|
t.integer "user_id"
t.integer "offer_id"
t.string "comment"
t.datetime "created_at"
t.datetime "updated_at"
end
in offer_controller.rb
#offers = User.find(current_user.id).offers.includes(:comments)
and in my index.html.erb
<% #offers.each do |airoffer| %>
<% airoffer.comments[0].comment %>
<% end %>
I know, it's not the better solution, but in the first time i will use it.