CODEWITHSUNDEEP
ruby-on-rails
user2950593
user2950593

Reputation: 9627

has_many or belongs_to works wrong

I have this two models:

class Answer < ActiveRecord::Base
  belongs_to :user
  belongs_to :question
  has_many :edits, dependent: :destroy
end

class Question < ActiveRecord::Base
  belongs_to :user
  has_many :answers, dependent: :destroy
end

But when I write in rails console following:

q=Question.new
q.save

a=Answer.new
a.question = q
a.save

q.answers.size

It gives me zero.

irb(main):026:0> q.answers.size
    => 0

But when I write this:

Answer.where(:question_id => q.id).size

it gives me 1

SO WHAT DO I DO?

In case you need it - answers and question migrations:

class CreateAnswers < ActiveRecord::Migration
  def change
    #execute "DROP TABLE #{:answers} CASCADE" 

    create_table :answers do |t|
      t.text :body
      t.references :user, index: true, foreign_key: true
      t.references :question, index: true, foreign_key: true

      t.timestamps null: false
    end
  end
end

class CreateQuestions < ActiveRecord::Migration
  def change
    #execute "DROP TABLE #{:questions} CASCADE" 
    create_table :questions do |t|
      t.string :title
      t.text :body
      t.references :user, index: true, foreign_key: true

      t.timestamps null: false
    end
  end
end

Upvotes: 0

Views: 41

Answers (1)

lei liu
lei liu

Reputation: 2775

You need to use inverse_of option in your relationship.

 class Answer < ActiveRecord::Base
   belongs_to :user
   belongs_to :question, inverse_of: answers
   has_many :edits, dependent: :destroy
 end

 class Question < ActiveRecord::Base
   belongs_to :user
   has_many :answers, inverse_of: question, dependent: :destroy
 end

So when you do:

 a.question = q

Rails will do this for you(in memory):

q.answers << a

And you don't need to reload the q again.

Upvotes: 2

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