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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.


To use it, add it to your Gemfile:

gem 'acts-as-taggable-on', '~> 9.0'

and bundle:


Post Installation

Install migrations

# For the latest versions :
rake acts_as_taggable_on_engine:install:migrations

Review the generated migrations then migrate :

rake db:migrate

If you do not wish or need to support multi-tenancy, the migration for add_tenant_to_taggings is optional and can be discarded safely.

For MySql users

You can circumvent at any time the problem of special characters issue 623 by setting in an initializer file:

ActsAsTaggableOn.force_binary_collation = true

Or by running this rake task:

rake acts_as_taggable_on_engine:tag_names:collate_bin

See the Configuration section for more details, and a general note valid for older version of the gem.



class User < ActiveRecord::Base
  acts_as_taggable_on :tags
  acts_as_taggable_on :skills, :interests #You can also configure multiple tag types per model

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 # save to persist tag_list

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 20.


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:
# NOTE: This only matches users that have the exact set of specified tags. If a user has additional tags, they are not returned.
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 have 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)

Wildcard tag search

You now have the following options for prefix, suffix and containment search, along with :any or :exclude option. Use wild: :suffix to place a wildcard at the end of the tag. It will be looking for awesome% and cool% in SQL. Use wild: :prefix to place a wildcard at the beginning of the tag. It will be looking for %awesome and %cool in SQL. Use wild: true to place a wildcard both at the beginning and the end of the tag. 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]

Finding tags based on context

You can find tags for a specific context by using the for_context scope:


Tag Parsers

If you want to change how tags are parsed, you can define 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:

ActsAsTaggableOn.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

Working with Owned Tags

Note that tag_list only returns tags whose taggings do not have an owner. Continuing from the above example:

@some_photo.tag_list # => []

To retrieve all tags of an object (regardless of ownership) or if only one owner can tag the object, use all_tags_list.

Adding owned tags

Note that owned tags are added all at once, in the form of comma seperated tags in string. Also, when you try to add owned tags again, it simply overwrites the previous set of owned tags. So to append tags in previously existing owned tags list, go as follows:

def add_owned_tag
    @some_item = Item.find(params[:id])
    owned_tag_list = @some_item.all_tags_list - @some_item.tag_list
    owned_tag_list += [(params[:tag])]
    @tag_owner.tag(@some_item, :with => stringify(owned_tag_list), :on => :tags)

def stringify(tag_list)
    tag_list.inject('') { |memo, tag| memo += (tag + ',') }[0..-1]
Removing owned tags

Similarly as above, removing will be as follows:

def remove_owned_tag
    @some_item = Item.find(params[:id])
    owned_tag_list = @some_item.all_tags_list - @some_item.tag_list
    owned_tag_list -= [(params[:tag])]
    @tag_owner.tag(@some_item, :with => stringify(owned_tag_list), :on => :tags)

Tag Tenancy

Tags support multi-tenancy. This is useful for applications where a Tag belongs to a scoped set of models:

class Account < ActiveRecord::Base
  has_many :photos

class User < ActiveRecord::Base
  belongs_to :account
  acts_as_taggable_on :tags
  acts_as_taggable_tenant :account_id

@user1.tag_list = ["foo", "bar"] # these taggings will automatically have the tenant saved
@user2.tag_list = ["bar", "baz"]

ActsAsTaggableOn::Tag.for_tenant( # returns Tag models for "foo" and "bar", but not "baz"

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 would like to have an exact match covering special characters with MySql:

ActsAsTaggableOn.force_binary_collation = true

If you would like to specify table names:

ActsAsTaggableOn.tags_table = 'aato_tags'
ActsAsTaggableOn.taggings_table = 'aato_taggings'

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 1: 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

NOTE 2: the option force_binary_collation is strongest than strict_case_match and when set to true, the strict_case_match is ignored. To roughly apply the force_binary_collation behaviour with a version of the gem <= 3.4.4, execute the following commands in the MySql console:

USE my_wonderful_app_db;




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


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.

Versions >= 4.x are compatible with Ruby 2.0.0+ and Rails 4 and 5.

Versions >= 7.x are compatible with Ruby 2.3.7+ and Rails 5 and 6.

Versions >= 8.x are compatible with Ruby 2.3.7+ and Rails 5 and 6.

Versions >= 9.x are compatible with Ruby 2.5.0 and Rails 6 and 7.

For an up-to-date roadmap, see


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 Github Actions, install and run wwtd.