Question

FIXED BY:
changing model names to match rails naming conventions

I’m getting the following error when I try to join a skill to a user:

 irb(main):006:0> user.skills << skill
NameError: uninitialized constant Users::Skill
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.1.3/lib/active_r
ecord/base.rb:1341:in `compute_type'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.1.3/lib/active_r
ecord/reflection.rb:173:in `klass'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.1.3/lib/active_r
ecord/associations/collection_association.rb:146:in `transaction'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.1.3/lib/active_r
ecord/associations/collection_association.rb:124:in `concat'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.1.3/lib/active_r
ecord/associations/collection_proxy.rb:118:in `<<'
        from (irb):6
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/comman
ds/console.rb:45:in `start'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/comman
ds/console.rb:8:in `start'
        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/comman
ds.rb:40:in `<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'
irb(main):007:0>

Here is my users.rb file:

class Users < ActiveRecord::Base

    has_and_belongs_to_many :skills

end

Here is my skills.rb file:

class Skills < ActiveRecord::Base

    has_and_belongs_to_many :users

end

And here is my schema.rb file:

ActiveRecord::Schema.define(:version => 20111214152402) do

  create_table "skills", :force => true do |t|
    t.integer  "user_id"
    t.string   "description", :null => false
    t.string   "skill_name",  :null => false
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  add_index "skills", ["user_id"], :name => "index_skills_on_user_id"

  create_table "users", :force => true do |t|
    t.integer  "skill_id"
    t.string   "first_name",   :limit => 25
    t.string   "last_name",    :limit => 50
    t.string   "email",                       :default => ""
    t.string   "password",     :limit => 40
    t.string   "location",     :limit => 100
    t.string   "status"
    t.text     "bio"
    t.string   "question1"
    t.string   "question2"
    t.string   "availability"
    t.string   "image"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  add_index "users", ["skill_id"], :name => "index_users_on_skill_id"

  create_table "users_skills", :id => false, :force => true do |t|
    t.integer "user_id"
    t.integer "page_id"
  end

  add_index "users_skills", ["user_id", "page_id"], :name => "index_users_skills_on_user_id_and_page_id"

end

If you can help that’d be awesome! If you need to see other files let me know.

Answer 1

user.skills is an array so in order to add a skill, you need to do

user.skills << skill

Additionally, on your schema, I notice that your user_skils table contains wrong foreign key id. I believe they should be user_id and skill_id.

Update

Your users table also looks wrong. You do not need a skill_id in your users table. Similarly, you do not need user_id in your skills table.

This is a small diagram of how the tables and attributes should look like

users            skills_users         skills
id      ---->    user_id
                 skill_id        ---> id

Update 2

Your model name looks wrong. It is a convention in RoR to use singular model name. Users should be User. Similarly, for skills.