gistfile1.rb

#config/initializers/datamapper_readonly.rb
module DataMapperReadOnly
  def read_only!
    [:valid?, :create, :update, :save, :destroy].each do |t|
      before t do
        raise Exception.new "read-only class attempted write"
      end
    end
  end
end	

DataMapper::Model.append_extensions DataMapperReadOnly

#app/models/Release.rb
class Release
  include DataMapper::Resource
  storage_names[:default] = 'releases'
  read_only!
  
  #..