production
        adapter: mysql
        database: myapp_development
        host: localhost
        username:
        password:

app - where you spend most time
  assets - where you put all static files, images, etc.
  controllers
  mailers - outbound mail. Not good to use because you can easily get flagged as spam
   (use a transactional email provider (stmp mailers) hosts such as mailgun, postmark, etc. )
   models
   views - where our erb goes
bin - where your executable code goes - we never touch this
application.rb - sets application defaults such as timezone, load path
enviornment folder - configurations for development and production, and testing.
                  - you can also create custom enviornments - such QA, intergration or staging
initializers folder - where you files that you want to load when your application
                    is initialized
Config folder
  locales - yml files - is a way to internationalize your app. Is comprised of comlicated hashes
        and you no longer write using strings. Extremely painful to manage files
Lib - you can also put assets in there
Tasks - you can place rake tasks in here
log - stores all terminal logs from your application
public - where you store your error pages
      - robosts - tell search engines where to go within your application
Vendor - a relic from the past
.gitignore - tells git what files to ignore when committing. (.files are hidden files)
Readme - is what is dispayed when you push your app to Github.

def change
    add_column :table_name :foreign_key (which is normally the resource+primary_key), :datatype (always will be integer)

    add_column :posts, :user_id, :integer
  end

Post.new(title: "some title", url: "some url", user = User.first)

You can run the following commands:
  user = User.first
  post = Post.first
  post.user **** virtual attribute
  post.title
  post.user_id = user ***NO, you can only set objects to object and integers to integers
  post.user_id = user_id

class Card
  attr_accessor :suit, :face_value

  def initialize(s,fv)
    @suit = s
    @face_value = fv
  end

  def pretty_output
    "The #{face_value} of #{find_suit}"
  end

  def to_s
    pretty_output
  end

  def find_suit
    ret_val = case suit
                when 'H' then 'Hearts'
                when 'D' then 'Diamonds'
                when 'S' then 'Spades'
                when 'C' then 'Clubs'
              end
    ret_val
  end
end

class Deck
  attr_accessor :cards

  def initialize
    @cards = []
    ['H', 'D', 'S', 'C'].each do |suit|
      ['2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A'].each do |face_value|
        @cards << Card.new(suit, face_value)
      end
    end
    scramble!
  end

  def scramble!
    cards.shuffle!
  end

  def deal_one
    cards.pop
  end

  def size
    cards.size
  end
end

module Hand
  def show_hand
    puts "---- #{name}'s Hand ----"
    cards.each do|card|
      puts "=> #{card}"
    end
    puts "=> Total: #{total}"
  end

  def total
    face_values = cards.map{|card| card.face_value }

    total = 0
    face_values.each do |val|
      if val == "A"
        total += 11
      else
        total += (val.to_i == 0 ? 10 : val.to_i)
      end
    end

    #correct for Aces
    face_values.select{|val| val == "A"}.count.times do
      break if total <= 21
      total -= 10
    end

    total
  end

  def add_card(new_card)
    cards << new_card
  end

  def is_busted?
    total > Blackjack::BLACKJACK_AMOUNT
  end
end

class Player
  include Hand

  attr_accessor :name, :cards

  def initialize(n)
    @name = n
    @cards = []
  end

  def show_flop
    show_hand
  end

end

class Dealer
  include Hand

  attr_accessor :name, :cards

  def initialize
    @name = "Dealer"
    @cards = []
  end

  def show_flop
    puts "---- Dealer's Hand ----"
    puts "=> First card is hidden"
    puts "=> Second card is #{cards[1]}"
  end
end

class Blackjack
  attr_accessor :deck, :player, :dealer

  BLACKJACK_AMOUNT = 21
  DEALER_HIT_MIN = 17

  def initialize
    @deck = Deck.new
    @player = Player.new("Player1")
    @dealer = Dealer.new
  end

  def set_player_name
    puts "What's your name?"
    player.name = gets.chomp
  end

  def deal_cards
    player.add_card(deck.deal_one)
    dealer.add_card(deck.deal_one)
    player.add_card(deck.deal_one)
    dealer.add_card(deck.deal_one)
  end

  def show_flop
    player.show_flop
    dealer.show_flop
  end

  def blackjack_or_bust?(player_or_dealer)
    if player_or_dealer.total == BLACKJACK_AMOUNT
      if player_or_dealer.is_a?(Dealer)
        puts "Sorry, dealer hit blackjack. #{player.name} loses."
      else
        puts "Congratulations, you hit blackjack! #{player.name} win!"
      end
      play_again?
    elsif player_or_dealer.is_busted?
      if player_or_dealer.is_a?(Dealer)
        puts "Congratulations, dealer busted. #{player.name} win!"
      else
        puts "Sorry, #{player.name} busted. #{player.name} loses."
      end
      play_again?
    end
  end

  def player_turn
    puts "#{player.name}'s turn."

    blackjack_or_bust?(player)

    while !player.is_busted?
      puts "What would you like to do? 1) hit 2) stay"
      response = gets.chomp

      if !['1', '2'].include?(response)
        puts "Error: you must enter 1 or 2"
        next
      end

      if response == '2'
        puts "#{player.name} chose to stay."
        break
      end

      #hit
      new_card = deck.deal_one
      puts "Dealing card to #{player.name}: #{new_card}"
      player.add_card(new_card)
      puts "#{player.name}'s total is now: #{player.total}"

      blackjack_or_bust?(player)
    end
    puts "#{player.name} stays at #{player.total}."
  end

  def dealer_turn
    puts "Dealer's turn."

    blackjack_or_bust?(dealer)
    while dealer.total < DEALER_HIT_MIN
      new_card = deck.deal_one
      puts "Dealing card to dealer: #{new_card}"
      dealer.add_card(new_card)
      puts "Dealer total is now: #{dealer.total}"

      blackjack_or_bust?(dealer)
    end
    puts "Dealer stays at #{dealer.total}."
  end

  def who_won?
    if player.total > dealer.total
      puts "Congratulations, #{player.name} wins!"
    elsif player.total < dealer.total
      puts "Sorry, #{player.name} loses."
    else
      puts "It's a tie!"
    end
    play_again?
  end

  def play_again?
    puts ""
    puts "Would you like to play again? 1) yes 2) no, exit"
    if gets.chomp == '1'
      puts "Starting new game..."
      puts ""
      deck = Deck.new
      player.cards = []
      dealer.cards = []
      start
    else
      puts "Goodbye!"
      exit
    end
  end

  def start
    set_player_name
    deal_cards
    show_flop
    player_turn
    dealer_turn
    who_won?
  end
end

game = Blackjack.new
game.start

class Board
  WINNING_LINES = [[1,2,3], [4,5,6], [7,8,9], [1,4,7], [2,5,8], [3,6,9], [1,5,9], [3,5,7]]

  def initialize
    @data = {}
    (1..9).each {|position| @data[position] = Square.new(' ') }
  end

  def empty_squares
    @data.select {|_, square| square.empty?}.values
  end

  def empty_positions
    @data.select {|_, square| square.empty?}.keys
  end

  def all_squares_marked?
    empty_squares.size == 0
  end

  def three_squares_in_a_row?(marker)
    WINNING_LINES.each do |line|
      return true if @data[line[0]].value == marker && @data[line[1]].value  == marker && @data[line[2]].value == marker
    end
    false
  end

  def mark_square(position, marker)
    @data[position].mark(marker)
  end

  def draw
    system 'clear'
    puts
    puts "     |     |"
    puts "  #{@data[1]}  |  #{@data[2]}  |  #{@data[3]}"
    puts "     |     |"
    puts "-----+-----+-----"
    puts "     |     |"
    puts "  #{@data[4]}  |  #{@data[5]}  |  #{@data[6]}"
    puts "     |     |"
    puts "-----+-----+-----"
    puts "     |     |"
    puts "  #{@data[7]}  |  #{@data[8]}  |  #{@data[9]}"
    puts "     |     |"
    puts
  end
end

class Player
  attr_reader :marker, :name
  def initialize(name, marker)
    @name = name
    @marker = marker
  end
end

class Square
  attr_reader :value

  def initialize(value)
    @value = value
  end

  def empty?
    @value == ' '
  end

  def mark(marker)
    @value = marker
  end

  def to_s
    @value
  end
end

class Game
  def initialize
    @board = Board.new
    @human = Player.new("James", "X")
    @computer = Player.new("R2D2", "O")
    @current_player = @human
  end

  def current_player_marks_square
    if @current_player == @human
      begin
        puts "Choose a position #{@board.empty_positions} to place a piece:"
        position = gets.chomp.to_i
      end until @board.empty_positions.include?(position)
    else
      position = @board.empty_positions.sample
    end
    @board.mark_square(position, @current_player.marker)
  end

  def alternate_player
    if @current_player == @human
      @current_player = @computer
    else
      @current_player = @human
    end
  end

  def current_player_wins?
    @board.three_squares_in_a_row?(@current_player.marker)
  end

  def play
    @board.draw
    loop do
      current_player_marks_square
      @board.draw
      if current_player_wins?
        puts "The winner is #{@current_player.name}!"
        break
      elsif @board.all_squares_marked?
        puts "It's a tie."
        break
      else
        alternate_player
      end
    end
    puts "Bye"
  end
end

Game.new.play

You must add the <script src="/application.js"></script> to the layout.erb
Google hosts Jquery for you!
1.x snippet: <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

$(document).ready(funtion(){
    $("element").click(funtion() {
        $(#player)_area).css('background-color', 'yellow')
        return false;===> do not re-execute
      });
  });

$(document).ready(function() {
  $('#hit_form input').click(function() {
    alert('hit button clicked!');
    return false;
    });
  });

$(document).ready(function() {
  #$('#hit_form input').click(function() { #must be rebind with the input again after indcating layout false
    $document).on(click, '#hit_form input', function()) {

    $.ajax({ #this is a hash, much include comma after entry
      type: 'POST',
      url: '/game/player/hit'
      #data: #also known as parameters
      )}.done(function(msg) {
        #$('#game').html(msg); #create div for game. Can't use HTML b/c its creating a duplicate game div id
        $('#game').replaceWith(msg);
        });
      });

    return false;
    });
  });

In main.rb:

get '/' do
  "Hello World" +params[:some].to_s
end

  get 'test/' do
    erb :test
  end

main.rb
get '/test' do
  @error = "We've got a problem"
  erb :test *** points to the test.erb template under the views***
end

#main.rb
get '/' do
  erb :set_name
end

#set_name.erb (Handles the display of data)
<h4> Set Player Name </h4>

<form action='/set_name' method='post'
  Name: <input type='text' name='player_name' />
  </br>
  <input type ='submit' class='btn'/>
</form>

#main.rb (handle the submission of the data)

post 'set_name' do
end

post '/set_name' do
  session[:player_name] = params[:player_name]
end

session[:turn] = session[:player_name]
      or
    session[:turn] = "dealer"

<form action='/new_player' method="post">
      <input type="text" name="player_name" />
      <br/>
      <input type="submit" class="btn btn-inverse" value="Let's Play!"/>
    </form>