Single Table Inheritance(STI) Problems - associations

Question

I'm new to rails and I'm having some problems specifying a couple of entities and relationships in my database.
Let's assume the following entities.
Racer Entity
Where the migration file looks like this:
class CreateRacers < ActiveRecord::Migration
def self.up
create_table :racers, options: "ENGINE=InnoDB" do |t|
t.string :email, limit: 60, null: false
end
add_index :racers, :email, unique: true
execute "ALTER TABLE racers MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
drop_table :racers
end
end
The model file looks like this:
class Racer < ActiveRecord::Base
attr_accessible :email
validates_uniqueness_of :email
before_save { |racer| racer.email = email.downcase }
# Email validation
VALID_EMAIL_REGEX = /([\w+.]+)#[a-z\d\-.]+\.[a-z]+\z/i
validates :email, presence: true, length: {maximum: 60}, format: { with: VALID_EMAIL_REGEX }
has_many :tracks, dependent: :delete_all
end
Track Entity
The migration file looks like this:
class CreateTracks < ActiveRecord::Migration
def self.up
create_table :tracks, options: "ENGINE=InnoDB" do |t|
t.column :user_id, 'integer unsigned', null: false
t.string :description, limit: 250, null: false
t.string :image, null: true
end
execute "ALTER TABLE tracks MODIFY id INT UNSIGNED AUTO_INCREMENT;"
add_foreign_key :tracks, :racers
end
def self.down
remove_foreign_key :tracks, :racers
drop_table :tracks
end
end
And the model file looks like this:
class Track < ActiveRecord::Base
attr_accessible :description, :image
validates :description, presence: true, length: {maximum: 250}
belongs_to :racer
validates_presence_of :racer_id
has_many :stops, dependent: :delete_all
end
Stop Entity
The migration file looks like this:
class CreateStops < ActiveRecord::Migration
def self.up
create_table :stops, options: "ENGINE=InnoDB" do |t|
t.column :track_id, 'integer unsigned', null: false
t.column :coordinates, :point, null: false
t.string :name, limit: 30, null: true
t.column :sequence_order, 'integer unsigned', null: false
end
execute "ALTER TABLE stops MODIFY id INT UNSIGNED AUTO_INCREMENT;"
add_foreign_key :stops, :tracks
end
def self.down
remove_foreign_key :stops, :tracks
drop_table :stops
end
end
And the model file looks like this:
class Stop < ActiveRecord::Base
attr_accessible :coordinates, :name, :sequence_order
validates :name, presence: true, length: {maximum: 30}
validates :coordinates, presence: true
validates :spot_sequence_order, presence: true
belongs_to :track
validates_presence_of :track_id
has_one :challenge, dependent: :delete_all
end
Challenge, Puzzle, Quiz, QuizOption entities (where the problem is)
Has seen above the Stop entity has_one challenge and I want that Challenge to be, among other things, a Quiz or a Puzzle. The Challenge belongs_to a Stop. So far I have the following migrations:
class CreatePuzzles < ActiveRecord::Migration
def self.up
create_table :puzzles, options: "ENGINE=InnoDB" do |t|
t.string :image_path, null: false
t.int :ver_split, null: false, default: 4
t.int :hor_split, null: false, default: 4
end
execute "ALTER TABLE puzzlies MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
drop_table :quizzes
end
end
class CreateQuizzes < ActiveRecord::Migration
def self.up
create_table :quizzes, options: "ENGINE=InnoDB" do |t|
t.string :question, null: false
end
execute "ALTER TABLE quizzes MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
drop_table :quizzes
end
end
And the following models
class Puzzle < ActiveRecord::Base
attr_accessor :image_path, :ver_split, hor_split
validates :image_path, presence: true, allow_blank: false
validates :ver_split, allow_blank: false
validates :hor_split, allow_blank: false
belongs_to :stop
end
class Quiz < ActiveRecord::Base
attr_accessor :question
validates :question, presence: true, length: { maximum: 255 }, allow_blank: false
belongs_to :spot
has_many :quiz_options
end
The Quiz has several answers, where one or more are correct.
class CreateQuizOptions < ActiveRecord::Migration
def self.up
create_table :quiz_options do |t|
t.column :quiz_id, 'integer unsigned', null: false
t.string :option, null: false
t.boolean :is_correct, null: false, default: false
end
add_foreign_key :quiz_options, :quizzes
execute "ALTER TABLE quiz_options MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
remove_foreign_key :quiz_options, :quizzes
drop_table :quiz_options
end
end
class QuizOption < ActiveRecord::Base
attr_accessor :option, :is_correct
validates :option, presence: true, length: { maximum: 255 }
validates_inclusion_of :is_correct, in: [true,false]
belongs_to :quiz
validates_presence_of :quiz_id
end
The Question
How should I specify my migrations,models and controllers to accomplish this goal?
I have found a couple of examples of STI and Polymorphic-Associations but I don't know which one to apply and how to apply them to this case.
First I have tried to use STI and declare all the necessary fields in the Challenge table and then the Quiz and Puzzle model inherit from Challenge model. The problem is that I don't know where to put the has_many :quiz_options.
Then I have tried to use Polymorphic-Associations explained here and here but I honestly can't understand how to adapt it to this specific case.
Thanks in advance.
Edit: I forgot to say that I'm using MySQL. I also have some gems to manage Spatial data types(rgeo, activerecord-mysql2spatial-adapter) and foreign_keys(foreigner).

Answer 1

Ok, I think I solved my own problem by applying Single Table Inheritance.
The result is not pretty but it works and due to the lack of proper information on other solutions I will stick to it by now.
So let's get back to my example.
The Racer, Track and Stop entity stay as they are, no changes there.
The Challenge migration will look like this:
class CreateChallenges < ActiveRecord::Migration
def self.up
create_table :challenges, options: "ENGINE=InnoDB" do |t|
t.column :stop_id, 'integer unsigned', null: false
t.string :type
# Common attributes to all challenges
t.string :description, null: false
# Puzzle attributes
t.string :image_path
t.int :vert_split
t.int :hor_split
# Quiz attributes
t.string :question
end
add_foreign_key :challenges, :stops
execute "ALTER TABLE quizzes MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
remove_foreign_key :challenges, :stops
drop_table :quizzes
end
end
In this table I just added all the necessary fields to specify both Quizzes and Puzzles.
Now the models will look like this:
class Challenge < ActiveRecord::Base
validates_presence_of :spot_id, :description
attr_accessible :description, :image_path
# Validate description attribute
validates :description, length: { maximum: 255 }, allow_blank: false
# Validates image type
VALID_IMAGE_TYPE_REGEX = /^[\/]?([\w]+[\/])*([\w]+\.(png|jpg))$/
validates :image_path, length: { maximum: 255 }, allow_blank: true, format: { with: VALID_IMAGE_TYPE_REGEX }
# Validates type attribute
validates_inclusion_of :type, in: %w( Quiz Puzzle )
# Associations
belongs_to :stop
has_many :quiz_options
end
class Puzzle < Challenge
validates_presence_of :image_path
attr_accessor :image_path, :ver_split, hor_split
validates :image_path, allow_blank: false
validates :ver_split, allow_blank: false
validates :hor_split, allow_blank: false
end
class Quiz < Challenge
validates_presence_of :question
attr_accessor :question
validates :question, length: { maximum: 255 }, allow_blank: false
end
Now to finish everything, the QuizOption migration and model will look like this:
class CreateQuizOptions < ActiveRecord::Migration
def self.up
create_table :quiz_options do |t|
t.column :challenge_id, 'integer unsigned', null: false
t.string :option, null: false
t.boolean :is_correct, null: false, default: false
end
add_foreign_key :quiz_options, :challenges
execute "ALTER TABLE quiz_options MODIFY id INT UNSIGNED AUTO_INCREMENT;"
end
def self.down
remove_foreign_key :quiz_options, :challenges
drop_table :quiz_options
end
end
class QuizOption < ActiveRecord::Base
validates_presence_of :challenge_id, :option
attr_accessor :option, :is_correct
validates :option, length: { maximum: 255 }
validates_inclusion_of :is_correct, in: [true,false]
belongs_to :challenge
end
This way everything works as I wanted.