Rails-Method-Nestable-(For-Nested-Forms).rb

# Add this snippet into your ApplicationHelper to make it available to all views
# This method enables a simple but clean way to handle nested forms when a :has_many relationship
# along with the :accepts_nested_attributes_for methods are invoked in the model.
# Instead of making a method for each of the first arguments of the form_for() method, you can now just
# invoke the "nestable()" method and pass in the object in the first argument, followed by any associated/nested models.
# See the method and example comments below

module ApplicationHelper

  # Call on first argument of the "form_for" method
  # form_for(nestable(@user, :phones, :addresses, :computers))
  def nestable(object, *nested_models)
    returning(object) do |o|
      nested_models.each do |nested_model|
        o.send(nested_model).build if o.send(nested_model).empty?
      end
    end
  end

end


# For a practical example: http://therailworld.com/posts/20-Nested-Object-Forms-in-Rails-2-3