gistfile1.txt

class Spot < ActiveRecord::Base
  belongs_to :badge_type
  has_and_belongs_to_many :badge_types
end


class BadgeType < ActiveRecord::Base
  #has_many :spots      
  has_and_belongs_to_many :spots
end

#solution

class Spot < ActiveRecord::Base
  belongs_to :attainable_badge, :class_name => "BadgeType", :foreign_key => "badge_type_id"
  has_and_belongs_to_many :redeemable_badges, :class_name => "BadgeType", :join_table => "badge_types_spots", :association_foreign_key => "badge_type_id"
end

class BadgeType < ActiveRecord::Base
  has_and_belongs_to_many :redeem_spots, :class_name => "Spot", :join_table => "badge_types_spots", :association_foreign_key => "spot_id"
  has_many :attain_spots, :class_name => "Spot"
end