# ActsAsTaggableOn
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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.

## Compatibility

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 https://github.com/mbleigh/acts-as-taggable-on/milestones

## Installation

To use it, add it to your Gemfile:

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

and bundle:

```shell
bundle
```

#### Post Installation

Install migrations

```shell
# 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 :
```shell
rake db:migrate
```

#### For MySql users
You can circumvent at any time the problem of special characters [issue 623](https://github.com/mbleigh/acts-as-taggable-on/issues/623) by setting in an initializer file:

```ruby
ActsAsTaggableOn.force_binary_collation = true
```

Or by running this rake task:

```shell
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.

#### Upgrading

see [UPGRADING](UPGRADING.md)

## Usage

Setup

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

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

@user = User.new(:name => "Bobby")
```

Add and remove a single tag

```ruby
@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

```ruby
@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](#configuration) for more about delimiter.

```ruby
@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.

```ruby
@user.tag_list = "awesome, slick, hefty"
@user.save
@user.reload
@user.tags
=> [#<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`.

```ruby
@user.skill_list = "joking, clowning, boxing"
@user.save
@user.reload
@user.skills
=> [#<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>]

@user.skill_list.add("coding")

@user.skill_list
# => ["joking", "clowning", "boxing", "coding"]

@another_user = User.new(:name => "Alice")
@another_user.skill_list.add("clowning")
@another_user.save

User.skill_counts
=> [#<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`:

```ruby
class User < ActiveRecord::Base
  # Alias for acts_as_ordered_taggable_on :tags
  acts_as_ordered_taggable
  acts_as_ordered_taggable_on :skills, :interests
end

@user = User.new(:name => "Bobby")
@user.tag_list = "east, south"
@user.save

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

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

### Finding most or least used tags

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

```ruby
ActsAsTaggableOn::Tag.most_used
ActsAsTaggableOn::Tag.least_used
```

You can also filter the results by passing the method a limit, however the default limit is 20.

```ruby
ActsAsTaggableOn::Tag.most_used(10)
ActsAsTaggableOn::Tag.least_used(10)
```

### 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.

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

User.tagged_with("awesome").by_join_date
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.


### Relationships

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.

```ruby
@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!)

```ruby
@user = User.new(:name => "Bobby")
@user.set_tag_list_on(:customs, "same, as, tag, list")
@user.tag_list_on(:customs) # => ["same", "as", "tag", "list"]
@user.save
@user.tags_on(:customs) # => [<Tag name='same'>,...]
@user.tag_counts_on(:customs)
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:

```ruby
class MyParser < ActsAsTaggableOn::GenericParser
  def parse
    ActsAsTaggableOn::TagList.new.tap do |tag_list|
      tag_list.add @tag_list.split('|')
    end
  end
end
```

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

```ruby
@user = User.new(:name => "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.add("north|west")
@user.tag_list # => ["north", "east", "south", "west"]
```

Or change it globally:

```ruby
ActsAsTaggable.default_parser = MyParser
@user = User.new(:name => "Bobby")
@user.tag_list = "east|south"
@user.tag_list # => ["east", "south"]
```

### Tag Ownership

Tags can have owners:

```ruby
class User < ActiveRecord::Base
  acts_as_tagger
end

class Photo < ActiveRecord::Base
  acts_as_taggable_on :locations
end

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

```ruby
@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:

```ruby
User.find(:first).posts.tag_counts_on(:tags)
```

A helper is included to assist with generating tag clouds.

Here is an example that generates a tag cloud.

Helper:

```ruby
module PostsHelper
  include ActsAsTaggableOn::TagsHelper
end
```

Controller:

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

View:

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

CSS:

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

## Configuration

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

```ruby
ActsAsTaggableOn.remove_unused_tags = true
```

If you want force tags to be saved downcased:

```ruby
ActsAsTaggableOn.force_lowercase = true
```

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

```ruby
ActsAsTaggableOn.force_parameterize = true
```

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

```ruby
ActsAsTaggableOn.strict_case_match = true
```

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

```ruby
ActsAsTaggableOn.force_binary_collation = true
```

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

```ruby
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](http://www.sqlite.org/src/artifact?ci=trunk&filename=ext/icu/README.txt)*

*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:*

```shell
USE my_wonderful_app_db;
ALTER TABLE tags MODIFY name VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_bin;
```

## Contributors

We have a long list of valued contributors. [Check them all](https://github.com/mbleigh/acts-as-taggable-on/contributors)

## Maintainer

* [Joost Baaij](https://github.com/tilsammans)

## TODO

- Write benchmark script
- Resolve concurrency issues

## Testing

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

```shell
bundle
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`](https://github.com/grosser/wwtd).


## License

See [LICENSE](https://github.com/mbleigh/acts-as-taggable-on/blob/master/LICENSE.md)
