1 # This class models a vertex in a directed graph.
2 class Vertex
< ActiveRecord
::Base
3 has_many
:sink_edges, :class_name => 'Edge', :foreign_key => 'source_id'
4 has_many
:sinks, :through => :sink_edges
6 has_and_belongs_to_many
:sources,
7 :class_name => 'Vertex', :join_table => 'edges',
8 :foreign_key => 'sink_id', :association_foreign_key => 'source_id'