representing a graph

I am representing a graph structrure in my DB. I have a table for nodes (which holds node names for now) and a table for segments/links. Each segment has the id-s of its 2 end-nodes. How do i specify this in the Rails model for a Segment ? I can't say belongs_to twice ... Is there a better way to do this ?

Something along these lines? This creates a directed graph, you would just add two segments for each node pair with the source/target reversed if you want an undirected graph.

## Models:

class Node < ActiveRecord::Base   has_many :segments   has_many :nodes, :through => :segments, :source => :target end

class Segment < ActiveRecord::Base   belongs_to :source, :class_name => "Node"   belongs_to :target, :class_name => "Node" end

## Migrations

create_table "nodes" do |t|   t.column "name", :string end create_table "segments" do |t|   t.column "source_id", :integer   t.column "target_id", :integer end

Best,

-r

Hi,