Tag

id
name

has_many :offer_items
has_many :offers, :through => :offer_items

Offer_item

id
tag_id
source_id

belongs_to :source
belongs_to :tag

Action:

@offer_item = OfferItem.find(params[:id])

def redirect
 redirect_to @offer_item.offer.url
 puts "Nu vet vi vilken tag han kom igenom: #{offer_item.tag}"
end

Offer

id
url
caption
description

has_many :offer_items
has_many :tags, :through => :offer_items