base_document.rb

module MyProject
  module Mongoid
    module Document
      extend ActiveSupport::Concern
      included do
        include ::Mongoid::Document
        include ::Mongoid::Timestamps
        include ::Mongoid::DotNotation
        include ::Mongoid::SearchForObject
      end
    end
  end
end

base_embedded_document.rb

module MyProject
  module Mongoid
    module EmbeddedDocument
      extend ActiveSupport::Concern
      included do
        include ::Mongoid::Document
        include ::Mongoid::RootFromEmbedded
        include ::Mongoid::DotNotation
        include ::Mongoid::SearchForObject
        include ::Mongoid::EmbeddedDocumentPath
      end
    end
  end
end

embedded_document_path.rb

  module Mongoid
    module EmbeddedDocumentPath
      extend ActiveSupport::Concern

      def embedded_document_path
        edp_get_parent_document(self)
      end

      private

      def edp_get_parent_document(element)
        retval = Array.new
        new_els = Array.new
        p = nil
        element.reflect_on_all_associations(:embedded_in).each do |r|
          p = element.send(r.name.to_s)
          unless p.nil?
            retval.unshift({klass: p.class.name, id: p.id})
            new_els = edp_get_parent_document(p)
            if new_els.length > 0
              new_els.reverse_each do |ne|
                retval.unshift(ne)
              end
            end
          end
        end
        retval
      end
    end
  end

mongoid_dot_notation.rb

module Mongoid
  #
  # Module DotNotation provides Embedded notation for Mongoid Documents
  #
  # Add to your mongoid document:
  # include Mongoid::EmbeddedNotation
  #
  # @author Leif Ringstad <leif@bitelm.com>
  #
  module DotNotation
    extend ActiveSupport::Concern

      #
      # Get dot notification for the current mongoid document. (embedded or not)
      #
      # Example
      #  farm_document
      #     has_many fields
      #  field_document
      #     has_many cows
      #
      # Calling on a cow will return "fields.cows"
      # Calling on a field will return "fields"
      # Calling on a farm will return ""
      #
      # @return [String] The dot notation for a given embedded document
      #
      def dot_notation
        dn = dot_notation_for_element_nested(self)
        if dn.nil?
          return ""
        else
          dn[0] = ''
        end
        dn
      end


    private

      #
      # Get dot notification for nested elements (nesting updwards)
      #
      # @param [Mongoid::Document] el A valid Mongoid:Document
      #
      # @return [String] The dot notation for a given element
      #
      def dot_notation_for_element_nested(el)
        # Get non-nil_embedded_relation
        p = get_embedded_relation(el)
        # puts p.inspect
        if p.nil?
          return nil
        else
          "#{dot_notation_for_element_nested(p[0])}.#{p[1].inverse_of}"
        end
      end

      #

      # Get the embedded relation of an object/element
      #
      # @param [Mongoid::Document] el A valid Mongoid:Document
      #
      # @returns Array [p, r] where p is the parent element for the embedded element, and
      #                       r is the inverse reflection name
      def get_embedded_relation(el)
        el.reflect_on_all_associations(:embedded_in).each do |r|
          # puts r.inspect
          p = el.send(r.name.to_s)
          return [p, r] unless p.nil?
        end
        nil
      end

  end
end

mongoid_root_from_embedded.rb

  module Mongoid
    # Add to your mongoid document:
    # include Mongoid::RootFromEmbedded
    # @author Leif Ringstad <leif@bitelm.com>
    module RootFromEmbedded
      extend ActiveSupport::Concern

      def root_from_embedded
        recurse_up_to_highest_element(self)
      end
      #
      # Recurse up to the highest element (root document)
      #
      #
      def recurse_up_to_highest_element(el)
        p = nil
        retval = nil
        el.reflect_on_all_associations(:embedded_in).each do |r|
          p     = el.send(r.name.to_s)
          unless p.nil?
            retval = recurse_up_to_highest_element(p)
            return p if retval.nil?
          end
        end
        retval
      end

    end
  end

mongoid_search_for_object.rb

module Mongoid
  # Add to your mongoid document:
  # include Mongoid::SearchForObject
  # @author Leif Ringstad <leif@bitelm.com>
  module SearchForObject
    extend ActiveSupport::Concern

      #
      # Search for a object given the dot notation, value and field
      #
      # @param [String] dn The dot notation to search for
      # @param [Array, BigDecimal, Boolean, Date, DateTime, Float, Hash, Integer, Moped::BSON::ObjectId, Moped::BSON::Binary, Range, Regexp, String, Symbol, Time, TimeWithZone] _value The value on the field to search for in any valid Mongoid type.
      # @param [Symbol] _field The field to search for the value. Default :id
      #
      # @return [Array] An array of embedded Mongoid documents
      #
      def search_for_object( dn, _value, _field = :id )
        return search_value_on_self(_value, _field) if dn.empty?
        dns          = dn.split(".")
        work_dn      = dns.shift
        remaining_dn = dns.join(".")
        retval = Array.new
        if remaining_dn.length == 0
          r = search_for_elements_in_array(work_dn, _value, _field)
          retval.concat(r) unless r.nil?
        else
          self.send(work_dn).each do |a|
            r = a.search_for_object(remaining_dn, _value, _field)
            retval.concat(r) unless r.nil?
          end
        end
        retval
      end

    private

      #
      # Find all elements within the array that matches value on a field
      #
      # @param [String] dn A dot notation with only one part. Should be a string that the object responds to has_one or has_many
      # @param [Array, BigDecimal, Boolean, Date, DateTime, Float, Hash, Integer, Moped::BSON::ObjectId, Moped::BSON::Binary, Range, Regexp, String, Symbol, Time, TimeWithZone] _value The value on the field to search for in any valid Mongoid type.
      # @param [Symbol] _field The field to search for the value. Default :id
      #
      # @return [<type>] <description>
      #
      def search_for_elements_in_array(dn, _value, _field = :id)
        return nil unless self.respond_to?(dn)
        self.send(dn).find_all {|e| e.send(_field) == _value}
      end

      #
      # Search for value on self
      #
      # @param [Array, BigDecimal, Boolean, Date, DateTime, Float, Hash, Integer, Moped::BSON::ObjectId, Moped::BSON::Binary, Range, Regexp, String, Symbol, Time, TimeWithZone] _value The value on the field to search for in any valid Mongoid type.
      # @param [Symbol] _field The field to search for the value. Default :id
      #
      # @return [self] <description>
      #
      def search_value_on_self(_value, _field)
        return [self] if (self.send(_field) == _value)
        nil
      end

  end

end