W7D2 Ruby Lecture

app.rb

require_relative 'app_config'
require_relative 'models/genre'
require_relative 'models/track'

AppConfig.establish_connection

genres = Genre.where(name: 'Rock') # get a collection that only has "Rock". .where always returns a collection of instances.

all_genres = Genre.all

genres.map do |genre|
   puts genre.Name
   genre.sayHi  # we can call class methods for Genre
end

song = Track.new name: "Cool new song", genre: genres[0]
song.save # Insert into DB

Track.create name: "Another Cool Song", genre: genres[0] # immediately creating and inserting a song into the DB

app_config.rb

require 'active_record'
require 'active_support/all'

module AppConfig

  DATABASE = 'chinook'

  DATABASE_PATH = File.absolute_path("#{DATABASE}.db", File.dirname(__FILE__))

  def self.establish_connection
    puts "Connecting to database '#{DATABASE_PATH}'"
    ActiveRecord::Base.establish_connection(
      adapter: 'sqlite3',
      database: DATABASE_PATH
    )
    ActiveRecord::Base.logger = Logger.new(STDOUT)
  end

end

Gemfile

source 'https://rubygems.org'

gem 'sqlite3'
gem 'activerecord'
gem 'activesupport'

genre.rb

class Genre < ActiveRecord::Base
    has_many :tracks
end

track.rb

class Track < ActiveRecord::Base
    belongs_to :genre

    def lyrics
        puts "Macarena!"
    end
end