I started playing around with datamapper to see if I could model an many to many parent/child relationship (self-referential habtm?) for an upcoming project. The plan was to use sproutcore for the gui (once I figured it out!), and merb as a webservice that it interacts with.

Justin gave me a kickstart with datamapper, and I eventually came up with:

#Person.rb
class Person
  include DataMapper::Resource

  property :id, Integer, :serial => true

  has n, :relationships
  has n, :parents, :through => :relationships, :class_name => 'Person'
  has n, :children, :through => :relationships, :class_name => 'Person'

  # parent = Person.create()
  # child = Person.create()
  # relationship = Relationship.new(:parent => parent)
  # child.relationships << relationship
  # child.save

end

#Relationship.rb
class Relationship
  include DataMapper::Resource

  property :id, Integer, :serial => true
  belongs_to :person
  belongs_to :parent, :class_name => 'Person'
  belongs_to :child, :class_name => 'Person'
end

I’ll eventually write some spec’s for it.

tags: datamapper merb