Models delete dependencies

app/models/album.rb

@@ -1,4 +1,4 @@
 class Album < ActiveRecord::Base
   belongs_to :artist
-  has_many :tracks, :order => 'bonus ASC, position ASC'
+  has_many :tracks, :order => 'bonus ASC, position ASC', :dependent => :destroy
 end

app/models/artist.rb

@@ -1,3 +1,3 @@
 class Artist < ActiveRecord::Base
-  has_many :albums, :order => 'year ASC, id ASC'
+  has_many :albums, :order => 'year ASC, id ASC', :dependent => :destroy
 end