Ruby reuse methods in DataMapper classes (helper)

Question

I'm trying to reuse methods in DataMapper classes. This might be as well a ruby question I think.

class Foo
  include DataMapper::Resource

  property :name
  property ...

  def self.special_name
    self.all(:name => 'whatever')
  end
end

class Bar
  include DataMapper::Resource

  property :name
  property ...

  def self.special_name
    self.all(:name => 'whatever')
  end
end

So the method special_name would be used for both classes as I want to get out the same result. But it also makes use of DataMapper methods like "all". So how would you do this?

Thx

Answer 1

module SpecialName
  def self.included(base)
    base.property :name, String
    base.extend ClassMethods
  end

  module ClassMethods
    def special_name
      all(:name => 'whatever')
    end
  end
end

class Foo
  include DataMapper::Resource
  include SpecialName
end

For more information on this include/extend idiom, see http://railstips.org/blog/archives/2009/05/15/include-vs-extend-in-ruby/.

Answer 2

module SpecialName


property :name
  def self.special_name
    self.all(:name => 'whatever')
  end
end

class Foo
  include DataMapper::Resource
  include SpecialName
end

class Bar
  include DataMapper::Resource
  include SpecialName
end

Answer 3

The "answer" is wrong. See the answer to this questions for more info: How to extend DataMapper::Resource with custom method

Short version: You need to use DataMapper's built-in extenders because a record/row and a model/table have different classes.

DataMapper::Model.append_extensions(MyModule::ClassMethods) #Add to model
DataMapper::Model.append_inclusions(MyModule::InstanceMethods) #Add to record