instiki/vendor/rails/railties/lib/rails_generator/generators/components/model/templates/migration.rb

class <%= migration_name %> < ActiveRecord::Migration
  def self.up
    create_table :<%= table_name %> do |t|
<% for  attribute in attributes -%>
      t.column :<%= attribute.name %>, :<%= attribute.type %>
<% end  -%>
    end
  end

  def self.down
    drop_table :<%= table_name %>
  end
end