Question

I’m trying to setup a simple has_many :through => association.

I have 3 models. user.rb, icon.rb and user_icon.rb.

user.rb…

class User < ActiveRecord::Base
  has_many :user_icons
  has_many :icons, :through => :user_icons
end

icon.rb…

class Icon < ActiveRecord::Base
  has_many :user_icons
  has_many :users, :through => :user_icons
end

user_icon.rb

class UserIcon < ActiveRecord::Base
  belongs_to :User
  belongs_to :Icon
end

As far as I can tell I’ve done everything correctly but when trying to run the following in the rails console…

User.first.icons

I get this error….

1.9.2-p290 :002 > User.first.icons
ActiveRecord::HasManyThroughSourceAssociationNotFoundError: Could not find the source association(s) :icon or :icons in model UserIcon. Try 'has_many :icons, :through => :user_icons, :source => <name>'. Is it one of :User or :Icon?
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/reflection.rb:517:in `check_validity!'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/associations/association.rb:27:in `initialize'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/associations/collection_association.rb:24:in `initialize'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/associations.rb:159:in `new'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/associations.rb:159:in `association'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.1.1/lib/active_record/associations/builder/association.rb:41:in `block in define_readers'
    from (irb):2
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.1/lib/rails/commands/console.rb:45:in `start'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.1/lib/rails/commands/console.rb:8:in `start'
    from /Users/jon/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.1.1/lib/rails/commands.rb:40:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

Any idea what I’m doing wrong here?

Answer 1

Your problem is in your associations in the UserIcon model. Case is important in defining your associations. If you change the models to lower case, it should work.

class UserIcon < ActiveRecord::Base
  belongs_to :user
  belongs_to :icon