relational models not working as expected - ruby-on-rails

Question

I created the following Active Record Schema using migrations but the relationships don't correspond to the schema. I've tried resetting, dropping, creating and migrating but in Rails C if i create a User u.User.create!(...), and then query u.groups or u.genres I get 'undefined method'
Thanks for your help
ActiveRecord::Schema.define(version: 20180603211047) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
create_table "genres", force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "tag"
t.bigint "user_id"
t.index ["user_id"], name: "index_genres_on_user_id"
end
create_table "genres_users", id: false, force: :cascade do |t|
t.bigint "user_id", null: false
t.bigint "genre_id", null: false
end
create_table "groups", force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "name"
t.bigint "user_id"
t.index ["user_id"], name: "index_groups_on_user_id"
end
create_table "groups_users", id: false, force: :cascade do |t|
t.bigint "user_id", null: false
t.bigint "group_id", null: false
end
create_table "playlists", force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "name"
t.string "link"
t.text "description"
t.bigint "group_id"
t.index ["group_id"], name: "index_playlists_on_group_id"
end
create_table "users", force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0, null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string "current_sign_in_ip"
t.string "last_sign_in_ip"
t.string "name"
t.string "token"
t.date "birthday"
t.string "link"
t.string "playlistId"
t.string "country"
t.index ["email"], name: "index_users_on_email", unique: true
t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
end
add_foreign_key "genres", "users"
add_foreign_key "groups", "users"
add_foreign_key "playlists", "groups"
end
here are the models:
class User < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
#before_action :authenticate_user!
has_and_belongs_to_many :genres, :through => :genres_users
has_and_belongs_to_many :groups, :through => :groups_users
include Enumerable
end
class Genre < ApplicationRecord
has_and_belongs_to_many :users, :through => :genres_users
end
class Group < ApplicationRecord
has_and_belongs_to_many :users, :through => :groups_users
has_one :playlist
end
class Playlist < ApplicationRecord
belongs_to :group
end
The relationship is that Groups have users, users have genres (favourite genres!), these are has and belongs to relationships through join tables (multiple genres per user and multiple groups per user). Every group has a playlist, and there will be multiple playlists

Answer 1

[Edited after clarification from OP]
The relationship is that Groups have users, users have genres (favourite genres!), these are has and belongs to relationships through join tables (multiple genres per user and multiple groups per user). Every group has a playlist, and there will be multiple playlists
First off, you don't need a user_id column on groups or genres as that's not how the setup should work.
class Genre < ApplicationRecord
has_many :favorite_genres
has_many :users, through: :favorite_genres
[... other stuff]
end
class User < ApplicationRecord
has_many :group_memberships
has_many :groups, through: :group_memberships
has_many :favorite_genres
has_many :users, through: :favorite_genres
[... other stuff]
end
class Group < ApplicationRecord
has_many :group_memberships
has_many :users, through: :group_memberships
has_many :playlists
[... other stuff]
end
class Playlist < ApplicationRecord
belongs_to :group
end
class GroupMemberships < ApplicationRecord
belongs_to :user
belongs_to :group
[... other stuff]
end
class FavoriteGenres < ApplicationRecord
belongs_to :user
belongs_to :genre
[... other stuff]
end
So you'd drop the user_id column in groups. The connection happens in :group_memberships (the table formerly known as users_groups), which is a user_id, a group_id, and then you can have additional metadata columns as you need them (e.g. admin boolean/role, etc)
. This is called a "Has Many Through" relationship (http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association)
Likewise, a user's favorite genres is setup with a through relationship. So you'll have a separate database table AND model file for those through joins.
I don't think you need your add_foreign_key calls at all at this level, nor many of your indexes. You'll probably do more eager loading or possibly add indexes on the thorugh join tables and you'd do those like this in the schema:
t.index ["user_id", "genre_id"], name: "index_favorite_genres_on_user_id_and_genre_id"
Remember that belongs_to now creates a validation for that to be present in 5.x. You can override this by adding optional: true on that line in the model, e.g. belongs_to :foo, optional: true
So all that being said, here's your new schema:
create_table "genres", id: :serial, force: :cascade do |t|
t.string "tag"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "groups", id: :serial, force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
create_table "favorite_genres", id: false, force: :cascade do |t|
t.bigint "user_id", null: false
t.bigint "genre_id", null: false
end
create_table "groups_memberships", id: false, force: :cascade do |t|
t.bigint "user_id", null: false
t.bigint "group_id", null: false
end
create_table "playlists", id: :serial, force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "name"
t.string "link"
t.text "description"
t.bigint "group_id"
t.index ["group_id"], name: "index_playlists_on_group_id"
end
create_table "users", id: :serial, force: :cascade do |t|
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0, null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string "current_sign_in_ip"
t.string "last_sign_in_ip"
t.string "name"
t.string "token"
t.date "birthday"
t.string "link"
t.string "playlistId"
t.string "country"
t.index ["email"], name: "index_users_on_email", unique: true
t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
end
Give that a whirl (I haven't built this in an app, so there may be some errors in the code) and you should now be able to do your console run:
u = User.create([values])
u.genres (should return nil until you create some relationships)
etc.