Using polymorphism for tags


#1

I have something like that:

class Commercial < ActiveRecord::Base
belongs_to :announcer
has_many :tags, :as=> :taggable
end

class Announcer < ActiveRecord::Base
has_many :commercials
has_many :tags, :as=> :taggable
end

class Tag < ActiveRecord::Base
belongs_to :taggable, :polymorphic => true
end

with commercials (id,name)
announcers(id,name)
tags(id,name,taggable_id,taggable_type)

now that’s not very DRY because I have several tags that repeat
themselves for different taggable_type.
is there a better way to deal with that?

thanx in advance

Pat


#2

You could turn tags into an intermediate join table on a “tag details”
class – although after typing it out it looks pretty ugly. You don’t
save that much unless your name column is going to be huge or unless
you’re going to store more information per tag (e.g. create date,
counter caches etc).

Schema:
tags(id, taggable_id, taggable_type)
tag_details(tag_id, name)

class Tag < ActiveRecord::Base
belongs_to :taggable, :polymorphic => true
has_one :tag_detail, :dependent => :destroy

def name
tag_detail.name
end

def name=(v)
tag_detail.name = v
end

def ensure_tag_detail
create_tag_detail
end
after_validation_on_create :ensure_tag_detail
end

class TagDetail < ActiveRecord::Base
belongs_to :tag
end


#3

ok thanx, I think I’ll stay with the first simple polymorphism solution.