gistfile1.rb

class Application
  include Mongoid::Document
  
  references_many :items
  references_many :templates
  references_many :users, :stored_as => :array, :inverse_of => :applications
end

class User
  include Mongoid::Document

  references_many :applications, :stored_as => :array, :inverse_of => :users
end

class Template
  include Mongoid::Document

  referenced_in :application
  embeds_many :fields
  references_many :items
end

class Field
  include Mongoid::Document
  
  embedded_in :template, :inverse_of => :fields
end

class Item
  include Mongoid::Document
  include Mongoid::Tree

  referenced_in :application
  referenced_in :template
  embeds_many :data
end

class Datum
  include Mongoid::Document

  embedded_in :item, :inverse_of => :data
end