show.haml

%h1
  = @song.title
%p
  Release Date: #{@song.released_on.strftime("%e %B %Y") if @song.released_on}
%p
  Length: #{@song.length/60} minutes #{@song.length%60} seconds
%pre
  = @song.lyrics
%p
  %a{href: "/songs"} Back to Songs Index
%p
  %a{href: "/songs/#{@song.id}/edit"} Edit this Song
%form{action: "/songs/#{@song.id}", method: "POST"}
  %input{type: "hidden", name: "_method", value: "DELETE"}
  %input{type: "submit", value: "Delete This Song"}

song.rb

require 'dm-core'
require 'dm-migrations'

DataMapper.setup(:default, "postgres://localhost/songsbysinatra")
DataMapper.finalize.auto_upgrade!

class Song
  include DataMapper::Resource
  property :id, Serial
  property :title, String
  property :lyrics, Text
  property :length, Integer
  property :released_on, Date
end

DataMapper.finalize

get '/songs' do
  @songs = Song.all
  haml :songs
end

get '/songs/:id' do
  @song = Song.get(params[:id])
  haml :show_song
end