The original source is from active_flag
class Profile < ActiveRecord::Base
flag :application, [:internal, :external_app_1, :external_2 ]
end
# {:english=>1, :spanish=>2, :chinese=>4, :french=>8, :japanese=>16 }
# Instance methods
profile.application #=> #<ActiveApp::Value: {:english, :japanese}>
profile.application.english? #=> true
profile.application.set?(:internal) #=> true
profile.application.unset?(:internal) #=> false
profile.application.set(:external_app_1)
profile.application.unset(:external_app_2)
profile.application.raw #=> 3
profile.application.to_a #=> [:external_app_1, :external_app_2]
profile.application = [:external_app_1, :external_app_2] # Direct assignment that works with forms
# Class methods
Profile.application.maps #=> {:internal=>1, :external_app_1=>2, :external_2=>4 }
Profile.application.humans #=> {:internal=>"Vertaling 1", :external_app_1=>"Vertaling 2" ...}
Profile.application.pairs #=> {"English"=>:english, "Spanish"=>:spanish, "Chinese"=>:chinese, "French"=>:french, "Japanese"=>:japanese}
# Scope methods
Profile.where_application(:external_app_1, :external_2) #=> SELECT * FROM profiles WHERE languages & 10 > 0
Profile.application.set_all!(:external_2) #=> UPDATE "profiles" SET languages = COALESCE(languages, 0) | 4
Profile.application.unset_all!(:external_2) #=> UPDATE "profiles" SET languages = COALESCE(languages, 0) & ~4
[](https://travis-ci.org/kenn/active_app)
Store up to 64 multiple applications ([bit array](https://en.wikipedia.org/wiki/Bit_array)) in a single integer column with ActiveRecord. From a UI standpoint, it can be used as a multi-select checkbox storage.
Perfect solution to store multiple boolean values such as preferences, notification settings, achievement status, profile options, etc. in a single column.
* **Single column to group multiple boolean values.** You don't need to have many separate columns. You don't even need a migration when you add a new application item to the list.
* **Fast bitwise operations.** `WHERE languages & 3 > 0` is faster than `WHERE (english = true) OR (spanish = true) OR ...`
If you want a simple enum column, take a look at [EnumAccessor](https://github.com/kenn/enum_accessor).
If you need to work with huge bit arrays, take a look at [Bitwise](https://github.com/kenn/bitwise).
## Usage
```ruby
class Profile < ActiveRecord::Base
flag :languages, [:english, :spanish, :chinese, :french, :japanese]
end
# {:english=>1, :spanish=>2, :chinese=>4, :french=>8, :japanese=>16 }
# Instance methods
profile.languages #=> #<ActiveApp::Value: {:english, :japanese}>
profile.languages.english? #=> true
profile.languages.set?(:english) #=> true
profile.languages.unset?(:english) #=> false
profile.languages.set(:spanish)
profile.languages.unset(:japanese)
profile.languages.raw #=> 3
profile.languages.to_a #=> [:english, :spanish]
profile.languages = [:spanish, :japanese] # Direct assignment that works with forms
# Class methods
Profile.languages.maps #=> {:english=>1, :spanish=>2, :chinese=>4, :french=>8, :japanese=>16 }
Profile.languages.humans #=> {:english=>"English", :spanish=>"Spanish", :chinese=>"Chinese", :french=>"French", :japanese=>"Japanese"}
Profile.languages.pairs #=> {"English"=>:english, "Spanish"=>:spanish, "Chinese"=>:chinese, "French"=>:french, "Japanese"=>:japanese}
# Scope methods
Profile.where_languages(:french, :spanish) #=> SELECT * FROM profiles WHERE languages & 10 > 0
Profile.languages.set_all!(:chinese) #=> UPDATE "profiles" SET languages = COALESCE(languages, 0) | 4
Profile.languages.unset_all!(:chinese) #=> UPDATE "profiles" SET languages = COALESCE(languages, 0) & ~4
gem 'active_app'Always set 0 as a default.
t.integer :languages, null: false, default: 0, limit: 8
# OR
add_column :users, :languages, :integer, null: false, default: 0, limit: 8limit: 8 is only required if you need more than 32 applications.
For a querying purpose, use where_[column] scope.
Profile.where_languages(:french) #=> SELECT * FROM profiles WHERE languages & 8 > 0Also takes multiple values.
Profile.where_languages(:french, :spanish) #=> SELECT * FROM profiles WHERE languages & 10 > 0By default, it searches with or operation, so the query above returns profiles that have either French or Spanish.
If you want to change it to and operation, you can specify:
Profile.where_languages(:french, :spanish, op: :and) #=> SELECT * FROM profiles WHERE languages = 10ActiveApp supports i18n just as ActiveModel does.
For instance, create a Japanese translation in config/locales/ja.yml
ja:
active_app:
profile:
languages:
english: 英語
spanish: スペイン語
chinese: 中国語
french: フランス語
japanese: 日本語and now to_human method returns a translated string.
I18n.locale = :ja
profile.languages.to_human #=> ['英語', 'スペイン語']
I18n.locale = :en
profile.languages.to_human #=> ['English', 'Spanish']Thanks to the translation support, forms just work as you would expect with the pairs convenience method.
# With FormBuilder
= form_for(@profile) do |f|
= f.collection_check_boxes :languages, Profile.languages.pairs
# With SimpleForm
= simple_form_for(@profile) do |f|
= f.input :languages, as: :check_boxes, collection: Profile.languages.pairsThere are plenty of gems that share the same goal. However they have messy syntax than necessary in my opinion, and I wanted a better API to achieve that goal.
Also, ActiveApp has one of the simplest code base that you can easily reason about or hack on.