Has-many-through model: NoMethodError

Question

In Rails 3.2.15, I'm trying to set up a has-many-through model called TopicInterest, to associate Users with Topics, with another attribute saved on TopicInterest called interest_type. After (I think) successfully setting up a join through a create() call to TopicInterest, I can't get the topic or user through the TopicInterest in the console:

irb(main):008:0> newjoin = TopicInterest.create(topic_id: mongo.id, user_id: me.id)
   (0.4ms)  BEGIN
  SQL (0.6ms)  INSERT INTO "topic_interests" ("created_at", "interest_type", "topic_id", "updated_at", "user_id") VALUES ($1, $2, $3, $4, $5) RETURNING "id"  [["created_at", Fri, 01 Aug 2014 16:10:00 UTC +00:00], ["interest_type", nil], ["topic_id", 1], ["updated_at", Fri, 01 Aug 2014 16:10:00 UTC +00:00], ["user_id", 1]]
   (6.4ms)  COMMIT
=> #<TopicInterest id: 2, user_id: 1, topic_id: 1, interest_type: nil, created_at: "2014-08-01 16:10:00", updated_at: "2014-08-01 16:10:00">
irb(main):009:0> newjoin.save
   (0.3ms)  BEGIN
   (0.3ms)  COMMIT
=> true
irb(main):010:0> newjoin.topic
NoMethodError: undefined method `topic' for #<TopicInterest:0x007fae2a06cc70>
    from /Users/duncanmalashock/.rvm/gems/ruby-1.9.3-p448@diver/gems/activemodel-3.2.15/lib/active_model/attribute_methods.rb:407:in `method_missing'
    from /Users/duncanmalashock/.rvm/gems/ruby-1.9.3-p448@diver/gems/activerecord-3.2.15/lib/active_record/attribute_methods.rb:149:in `method_missing'
    from (irb):10
    from /Users/duncanmalashock/.rvm/gems/ruby-1.9.3-p448@diver/gems/railties-3.2.15/lib/rails/commands/console.rb:47:in `start'
    from /Users/duncanmalashock/.rvm/gems/ruby-1.9.3-p448@diver/gems/railties-3.2.15/lib/rails/commands/console.rb:8:in `start'
    from /Users/duncanmalashock/.rvm/gems/ruby-1.9.3-p448@diver/gems/railties-3.2.15/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

User model:

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :first_name, :last_name, :email, :password, :password_confirmation, :remember_me
  has_many :topics, through: :topic_interests
end

Topic model:

class Topic < ActiveRecord::Base
  attr_accessible :name, :description
  has_many :users, through: :topic_interests
end

TopicInterest model:

class TopicInterest < ActiveRecord::Base
  attr_accessible :interest_type, :user_id, :topic_id
end

What am I doing wrong? Many thanks for any help.

RAJ RAJ · Accepted Answer · 2014-08-01T16:22:17

You need to add belongs_to references in your topic_interest.rb model

class TopicInterest < ActiveRecord::Base
  attr_accessible :interest_type, :user_id, :topic_id
  belongs_to :topic
  belongs_to :user
end

Edit:

As Duncan Malashock has detected that there was missing another direct association in this models, I adding that here for proper reference.

user.rb and topic.rb model should have direct association with topic_interests too.

Need to add has_many :topic_interests in both the mentioned models.

Has-many-through model: NoMethodError

1 Answers