title: Why are the methods up and down not being created with my subclass of ActiveRecord::Migration?
body: <p>I'm reading Rails 3 in Action and following the commands verbatim. However, when I run the commands</p>
  
  <pre><code>rails new things_i_bought
  cd things_i_bought
  bundle install
  rails generate scaffold purchase name:string cost:float
  </code></pre>
  
  <p>The book says I should get this code:</p>
  
  <pre><code>class CreatePurchases &lt; ActiveRecord::Migration
            def self.up #not created in my code
              create_table :purchases do |t|
                t.string :name
                t.float :cost
                t.timestamps
              end
  end
            def self.down # not created in my code
              drop_table :purchases
  end
   end
  </code></pre>
  
  <p>I get this code instead:</p>
  
  <pre><code>class CreatePurchases &lt; ActiveRecord::Migration
    def change
      create_table :purchases do |t|
        t.string :name
        t.float :cost
  
        t.timestamps
      end
    end
  end
  </code></pre>
  
  <p>Why are the class methods up and down not being created for me? I'm using 
  rails 3.1.1 and ruby 1.9.2.</p>