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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.


Versions 2.x are compatible with Ruby 1.8.7+ and Rails 3.

Versions 2.4.1 and up are compatible with Rails 4 too (thanks to arabonradar and cwoodcox).

Versions >= 3.x are compatible with Ruby 1.9.3+ and Rails 3 and 4.

For an up-to-date roadmap, see


To use it, add it to your Gemfile:

gem 'acts-as-taggable-on', '~> 3.4'

and bundle:


Post Installation

Install migrations

# For the latest versions :
rake acts_as_taggable_on_engine:install:migrations
# For versions 2.4.1 and earlier :
rails generate acts_as_taggable_on:migration

Review the generated migrations then migrate :

rake db:migrate





class User < ActiveRecord::Base
  acts_as_taggable # Alias for acts_as_taggable_on :tags
  acts_as_taggable_on :skills, :interests

class UsersController < ApplicationController
  def user_params
    params.require(:user).permit(:name, :tag_list) ## Rails 4 strong params usage

@user = => "Bobby")

Add and remove a single tag

@user.tag_list.add("awesome")   # add a single tag. alias for <<
@user.tag_list.remove("awesome") # remove a single tag

Add and remove multiple tags in an array

@user.tag_list.add("awesome", "slick")
@user.tag_list.remove("awesome", "slick")

You can also add and remove tags in format of String. This would be convenient in some cases such as handling tag input param in a String.

Pay attention you need to add parse: true as option in this case.

You may also want to take a look at delimiter in the string. The default is comma , so you don't need to do anything here. However, if you made a change on delimiter setting, make sure the string will match. See configuration for more about delimiter.

@user.tag_list.add("awesome, slick", parse: true)
@user.tag_list.remove("awesome, slick", parse: true)

You can also add and remove tags by direct assignment. Note this will remove existing tags so use it with attention.

@user.tag_list = "awesome, slick, hefty"
=> [#<ActsAsTaggableOn::Tag id: 1, name: "awesome", taggings_count: 1>,
 #<ActsAsTaggableOn::Tag id: 2, name: "slick", taggings_count: 1>,
 #<ActsAsTaggableOn::Tag id: 3, name: "hefty", taggings_count: 1>]

With the defined context in model, you have multiple new methods at disposal to manage and view the tags in the context. For example, with :skill context these methods are added to the model: skill_list(and skill_list.add, skill_list.remove skill_list=), skills(plural), skill_counts.

@user.skill_list = "joking, clowning, boxing"
=> [#<ActsAsTaggableOn::Tag id: 1, name: "joking", taggings_count: 1>,
 #<ActsAsTaggableOn::Tag id: 2, name: "clowning", taggings_count: 1>,
 #<ActsAsTaggableOn::Tag id: 3, name: "boxing", taggings_count: 1>]


# => ["joking", "clowning", "boxing", "coding"]

@another_user = => "Alice")

=> [#<ActsAsTaggableOn::Tag id: 1, name: "joking", taggings_count: 1>,
 #<ActsAsTaggableOn::Tag id: 2, name: "clowning", taggings_count: 2>,
 #<ActsAsTaggableOn::Tag id: 3, name: "boxing", taggings_count: 1>]

To preserve the order in which tags are created use acts_as_ordered_taggable:

class User < ActiveRecord::Base
  # Alias for acts_as_ordered_taggable_on :tags
  acts_as_ordered_taggable_on :skills, :interests

@user = => "Bobby")
@user.tag_list = "east, south"

@user.tag_list = "north, east, south, west"

@user.tag_list # => ["north", "east", "south", "west"]

Finding most or least used tags

You can find the most or least used tags by using:


You can also filter the results by passing the method a limit, however the default limit is 50.


Finding Tagged Objects

Acts As Taggable On uses scopes to create an association for tags. This way you can mix and match to filter down your results.

class User < ActiveRecord::Base
  acts_as_taggable_on :tags, :skills
  scope :by_join_date, order("created_at DESC")

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

# Find users that matches all given tags:
User.tagged_with(["awesome", "cool"], :match_all => true)

# Find users with any of the specified tags:
User.tagged_with(["awesome", "cool"], :any => true)

# Find users that has not been tagged with awesome or cool:
User.tagged_with(["awesome", "cool"], :exclude => true)

# Find users with any of the tags based on context:
User.tagged_with(['awesome', 'cool'], :on => :tags, :any => true).tagged_with(['smart', 'shy'], :on => :skills, :any => true)

You can also use :wild => true option along with :any or :exclude option. It will be looking for %awesome% and %cool% in SQL.

Tip: User.tagged_with([]) or User.tagged_with('') will return [], an empty set of records.


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.tagged_with("same", :on => :customs) # => [@user]

Tag Parsers

If you want to change how tags are parsed, you can define a your own implementation:

class MyParser < ActsAsTaggableOn::GenericParser
  def parse do |tag_list|
      tag_list.add @tag_list.split('|')

Now you can use this parser, passing it as parameter:

@user = => "Bobby")
@user.tag_list = "east, south"
@user.tag_list.add("north|west", parser: MyParser)
@user.tag_list # => ["north", "east", "south", "west"]

# Or also:
@user.tag_list.parser = MyParser
@user.tag_list # => ["north", "east", "south", "west"]

Or change it globally:

ActsAsTaggable.default_parser = MyParser
@user = => "Bobby")
@user.tag_list = "east|south"
@user.tag_list # => ["east", "south"]

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)
Photo.tagged_with("paris", :on => :locations, :owned_by => @some_user)
@some_photo.locations_from(@some_user) # => ["paris", "normandy"]
@some_photo.owner_tags_on(@some_user, :locations) # => [#<ActsAsTaggableOn::Tag id: 1, name: "paris">...]
@some_photo.owner_tags_on(nil, :locations) # => Ownerships equivalent to saying @some_photo.locations
@some_user.tag(@some_photo, :with => "paris, normandy", :on => :locations, :skip_save => true) #won't save @some_photo object

Dirty objects

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

@bobby.skill_list_changed? #=> false
@bobby.changes #=> {}

@bobby.skill_list = "swimming"
@bobby.changes.should == {"skill_list"=>["jogging, diving", ["swimming"]]}
@bobby.skill_list_changed? #=> true

@bobby.skill_list_change.should == ["jogging, diving", ["swimming"]]

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 a 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 ActsAsTaggableOn::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; }


If you would like to remove unused tag objects after removing taggings, add:

ActsAsTaggableOn.remove_unused_tags = true

If you want force tags to be saved downcased:

ActsAsTaggableOn.force_lowercase = true

If you want tags to be saved parametrized (you can redefine to_param as well):

ActsAsTaggableOn.force_parameterize = true

If you would like tags to be case-sensitive and not use LIKE queries for creation:

ActsAsTaggableOn.strict_case_match = true

If you want to change the default delimiter (it defaults to ','). You can also pass in an array of delimiters such as ([',', '|']):

ActsAsTaggableOn.delimiter = ','

NOTE: SQLite by default can't upcase or downcase multibyte characters, resulting in unwanted behavior. Load the SQLite ICU extension for proper handle of such characters. See docs


We have a long list of valued contributors. Check them all



  • Write benchmark script
  • Resolve concurrency issues


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

rake spec

You can run all the tests across all the Rails versions by running rake appraise. If you'd also like to run the tests across all rubies and databases as configured for Travis CI, install and run wwtd.