CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-3
user592638
user592638

Reputation:

joining 3 tables or more with active record

Let say I have 3 tables:

schools{id, name, desc, adress}
reviews{id, content, rating, school_id, user_id} # user_id & schoold_id is foregin keys
users{id, name, city}

How do I write a rails scope or method the joins all 3 tables and grab the column the schools.name , reviews.content and reviews.rating, the users.name

I tried somehting this, but it only return the review data and not the joining part.

Review.joins(:school, :user).select("content, rating, schools.name, users.name").all

I am using rails 3.2

Upvotes: 1

Views: 262

Answers (1)

vlasits
vlasits

Reputation: 2235

You just need to define has-many :through relationships for schools and users like this:

class School < ActiveRecord::Base
  has_many :users, :through => :reviews 
end
class Review < ActiveRecord::Base
  belongs_to :users
  belongs_to :schools
end
class User < ActiveRecord::Base
  has_many schools, :through => reviews
end

In your Review controller you can do

def index
  @reviews = Review.all
end

Then in your views each review object will have a school and a user associated with it, so you would just do:

review.content, review.rating, review.user.name, review.school.name

Reading this will help you understand why: http://guides.rubyonrails.org/association_basics.html

Upvotes: 1

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