Fetching contributors…
Cannot retrieve contributors at this time
200 lines (137 sloc) 6.29 KB


This plugin was originally based on Acts as Taggable on Steroids by Jonathan Viney. It has evolved substantially since that point, but all credit goes to him for the initial tagging functionality that so many people have used.

For instance, in a social network, a user might have tags that are called skills, interests, sports, and more. There is no real way to differentiate between tags and so an implementation of this type is not possible with acts as taggable on steroids.

Enter Acts as Taggable On. Rather than tying functionality to a specific keyword (namely “tags”), acts as taggable on allows you to specify an arbitrary number of tag “contexts” that can be used locally or in combination in the same way steroids was used.



Acts As Taggable On is available both as a gem and as a traditional plugin. For the traditional plugin you can install like so (Rails 2.1 or later):

script/plugin install git://


Acts As Taggable On is also available as a gem plugin using Rails 2.1's gem dependencies. To install the gem, add this to your config/environment.rb:

config.gem "acts-as-taggable-on", :source => ""

After that, you can run “rake gems:install” to install the gem if you don't already have it.

Post Installation (Rails)

  1. script/generate acts_as_taggable_on_migration

  2. rake db:migrate


Acts As Taggable On uses RSpec for its test coverage. Inside the plugin directory, you can run the specs with:

rake spec

If you already have RSpec on your application, the specs will run while using:

rake spec:plugins


class User < ActiveRecord::Base
  acts_as_taggable_on :tags, :skills, :interests

@user = => "Bobby")
@user.tag_list = "awesome, slick, hefty"      # this should be familiar
@user.skill_list = "joking, clowning, boxing" # but you can do it for any context!
@user.skill_list # => ["joking","clowning","boxing"] as TagList

@user.tags # => [<Tag name:"awesome">,<Tag name:"slick">,<Tag name:"hefty">]
@user.skills # => [<Tag name:"joking">,<Tag name:"clowning">,<Tag name:"boxing">]

# The old way
User.find_tagged_with("awesome", :on => :tags) # => [@user]
User.find_tagged_with("awesome", :on => :skills) # => []

# The better way (utilizes named_scope)
User.tagged_with("awesome", :on => :tags) # => [@user]
User.tagged_with("awesome", :on => :skills) # => []

@frankie = User.create(:name => "Frankie", :skill_list => "joking, flying, eating")
User.skill_counts # => [<Tag name="joking" count=2>,<Tag name="clowning" count=1>...]

Finding Tagged Objects

Acts As Taggable On utilizes Rails 2.1's named_scope to create an association for tags. This way you can mix and match to filter down your results, and it also improves compatibility with the will_paginate gem:

class User < ActiveRecord::Base
  acts_as_taggable_on :tags
  named_scope :by_join_date, :order => "created_at DESC"

User.tagged_with("awesome").by_date.paginate(:page => params[:page], :per_page => 20)


You can find objects of the same type based on similar tags on certain contexts. Also, objects will be returned in descending order based on the total number of matched tags.

@bobby = User.find_by_name("Bobby")
@bobby.skill_list # => ["jogging", "diving"]

@frankie = User.find_by_name("Frankie")
@frankie.skill_list # => ["hacking"]

@tom = User.find_by_name("Tom")
@tom.skill_list # => ["hacking", "jogging", "diving"]

@tom.find_related_skills # => [<User name="Bobby">,<User name="Frankie">]
@bobby.find_related_skills # => [<User name="Tom">] 
@frankie.find_related_skills # => [<User name="Tom">]

Dynamic Tag Contexts

In addition to the generated tag contexts in the definition, it is also possible to allow for dynamic tag contexts (this could be user generated tag contexts!)

@user = => "Bobby")
@user.set_tag_list_on(:customs, "same, as, tag, list")
@user.tag_list_on(:customs) # => ["same","as","tag","list"]
@user.tags_on(:customs) # => [<Tag name='same'>,...]
User.find_tagged_with("same", :on => :customs) # => [@user]

Tag Ownership

Tags can have owners:

class User < ActiveRecord::Base

class Photo < ActiveRecord::Base
  acts_as_taggable_on :locations

@some_user.tag(@some_photo, :with => "paris, normandy", :on => :locations)

Tag cloud calculations

To construct tag clouds, the frequency of each tag needs to be calculated. Because we specified acts_as_taggable_on on the User class, we can get a calculation of all the tag counts by using User.tag_counts_on(:customs). But what if we wanted a tag count for an single user's posts? To achieve this we call tag_counts on the association:


A helper is included to assist with generating tag clouds.

Here is an example that generates a tag cloud.


module PostsHelper
  include TagsHelper


class PostController < ApplicationController
  def tag_cloud
    @tags = Post.tag_counts_on(:tags)


<% tag_cloud(@tags, %w(css1 css2 css3 css4)) do |tag, css_class| %>
  <%= link_to, { :action => :tag, :id => }, :class => css_class %>
<% end %>


.css1 { font-size: 1.0em; }
.css2 { font-size: 1.2em; }
.css3 { font-size: 1.4em; }
.css4 { font-size: 1.6em; }


  • TomEric (i76) - Maintainer

  • Michael Bleigh - Original Author

  • Brendan Lim - Related Objects

  • Pradeep Elankumaran - Taggers

  • Sinclair Bain - Patch King

Patch Contributors

  • tristanzdunn - Related objects of other classes

  • azabaj - Fixed migrate down

  • Peter Cooper - named_scope fix

  • slainer68 - STI fix

  • harrylove - migration instructions and fix-ups

  • lawrencepit - cached tag work

  • sobrinho - fixed tag_cloud helper

Copyright © 2007-2009 Michael Bleigh ( and Intridea Inc. (, released under the MIT license