gistfile1.rb

class CreateBooks < ActiveRecord::Migration
  def self.up
    create_table :books do |t|
      t.string :title, :null => false
      t.text :description
      t.string :isbn
      t.belongs_to :authorship

      t.timestamps
    end
  end

  def self.down
    drop_table :books
  end
end


class CreateAuthors < ActiveRecord::Migration
  def self.up
    create_table :authors do |t|
      t.string :name, :null => false
      t.string :about_author
      t.belongs_to :authorship

      t.timestamps
    end
  end

  def self.down
    drop_table :authors
  end
end

class CreateAuthorships < ActiveRecord::Migration
  def self.up
    create_table :authorships do |t|
      t.integer :author_id, :null => false
      t.integer :book_id, :null => false

      t.timestamps
    end
  end

  def self.down
    drop_table :authorships
  end
end


#models

class Author < ActiveRecord::Base
  has_many :authorships
  has_many :books, :through => :authorships
end

class Book < ActiveRecord::Base
  has_many :authorships
  has_many :authors, :through => :authorships
end

class Authorship < ActiveRecord::Base
  belongs_to :author
  belongs_to :book
end