SimpleSet

A Rails plugin which brings easy-to-use set-like functionality to ActiveRecord models.

This is based on SimpleEnum.

Installation

Add this line to your application's Gemfile:

gem 'simple_set'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simple_set

Usage

Add this to a model:

class User < ActiveRecord::Base
  as_set :roles, [:accounting, :management]
end

Then create the required roles_cd column using migrations:

class AddRolesToUsers < ActiveRecord::Migration
  def change
    add_column :users, :roles_cd, :integer
  end
end

Now, it's possible to manage roles with maximum ease:

bob = User.new
bob.roles = [:accounting]
bob.accounting?           #=> true
bob.management?           #=> false
bob.roles                 #=> [:accounting]
bob.roles_cd              #=> 1

Gotchas

Acceptable values can be provided as an Array or as a Hash, the following lines are equivalent:

   as_set :spoken_languages, [:english, :french, :german, :japanese]
   as_set :spoken_languages, {english: 1, french: 2, german: 4, japanese: 8}

Reordering the array will change each element's value which is likely unwanted. Either only append new elements to the Array notation or use the Hash notation.

Although the Hash notation is less intuitive than the Array notation, it allows some neat tricks:

   class Pixel
     as_set :rgb, {
       red: 1,
       green: 2,
       blue: 4,

       yellow: 3,
       magenta: 5,
       cyan: 6,
       white: 7,
     }
   end

   x = Pixel.create(rgb: [:red, :blue])
   x.red?          #=> true
   x.green?        #=> false
   x.blue?         #=> true

   x.yellow?       #=> false
   x.magenta?      #=> true
   x.cyan?         #=> false

   x.white?        #=> false

   x.green = true
   x.white?        #=> true

If the shortcut methods (like <symbol>?, <symbol>= or Klass.<symbol>) conflict with something in your class, an error will be raised. You can avoid this situation by defining a prefix:

   class Lp < ActiveRecord::Base
     # Without :prefix, the :new media condition bellow would generate a
     # Lp::new method that returns 1 and overrides the constructor.  This is
     # likely unwanted and a :prefix must be set to avoid this situation:
     as_set :media_conditions, [:new, :sealed, :very_good, :good, :fair, :poor], prefix: true
   end

   Lp.media_condition_new #=> 1
   Lp.new                 #=> #<Lp:0x00000803c22b98>

When :prefix is set to true, shortcut methods are prefixed by the singularized name of the attribute.

The :prefix option not only takes a boolean value as an argument, but instead can also be supplied a custom prefix (i.e. any string or symbol), so with prefix: 'foo' all shortcut methods would look like: foo_<symbol>...

Sometimes it might be useful to disable the generation of the shortcut methods (<symbol>?, <symbol>= and Klass.<symbol>), to do so just add the option slim: true:

   class User
     as_set :spoken_languages, [:english, :french, :german, :japanese], slim: true
   end

   bob = User.create(spoken_languages: [:english, :french]
   bob.spoken_languages #=> [:english, :french]
   bob.french?          #=> throws NoMethodError: undefined method `french?'
   bob.french = false   #=> throws NoMethodError: undefined method `french='
   User.french          #=> throws NoMethodError: undefined method `french'

Easy Rails integration:

Given a User is declared as:

   class User < ActiveRecord::Base
     as_set :roles, [:management, :accounting, :human_resources]
   end

Adjust strong parameters to allow roles assignment:

   params.require(:user).permit(:roles => [])

And then render a collection of checkboxes:

   = form_for @user do |f|
     = f.collection_check_boxes(:roles, User.roles, :to_sym, :to_sym) do |b|
       = b.check_box
       = b.label do
         = t("application.roles.#{b.text}")

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request