class Procedure
  include DataMapper::Resource

  property :id, Serial
  property :title, String
  property :body, String
  property :create_date, DateTime
  property :last_reviewed, DateTime

  has n, :related_procedures
  has n, :procedures, :through => :related_procedures

  has n, :procedure_authors
  has n, :users, :through => :Procedure_authors

  has n, :procedure_endorsements
  has n, :users, :through => :procedure_endorsements

end

class RelatedProcedure
  include DataMapper::Resource

  property :parent_procedure_id, Integer, :key => true
  property :child_procedure_id, Integer, :key => true

  belongs_to :procedure

end


class ProcedureAuthor
  include DataMapper::Resource

  property :id,         Serial

  belongs_to :procedure
  belongs_to :user

end

class User
  include DataMapper::Resource

  property :id,     Serial
  property :login,  String
  property :title, String
  property :first_name, String
  property :last_name, String

  has n, :procedure_authors
  has n, :procedures, :through => :procedure_authors

  has n, :procedure_endorsements
  has n, :procedures, :through => :procedure_endorsements

end

nick = User[1]
sequence = Procedure [1]

ProcedureAuthor.new(:User => nick, :Procedure => sequence)

NameError: uninitialized constant ProcedureAuthor::Procedure_association
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/associations/many_to_one.rb:21:in `Procedure='
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/resource.rb:498:in `send'
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/resource.rb:498:in `attributes='
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/resource.rb:494:in `each_pair'
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/resource.rb:494:in `attributes='
  from /Library/Ruby/Gems/1.8/gems/dm-core-0.9.6/lib/dm-core/resource.rb:576:in `initialize'
  from (irb):7:in `new'
  from (irb):7
  from :0