rails model has_many of itself

This is a self-referential model, you can try something like this:

class Event < ActiveRecord::Base
  belongs_to :parent, :class_name => "Event", :foreign_key => "parent_event_id"
  has_many :child_events, :class_name => "Event", :foreign_key => "child_event_id"
end

That way, you can call @event.parent to get an ActiveRecord Event object and @event.child_events to get an ActiveRecord collection of Event objects