`attr_bitwise`

Bitwise attribute for ruby class and Rails model

Features

bitwise attribute + helpers, useful for storing multiple states in one place
ActiveRecord compatible

Please read this article for some concrete examples

Install

Inline

gem install attr_bitwise

Gemfile

gem 'attr_bitwise'

Usage

attr_bitwise :<name>, mapping: <values_sym> [, column_name: <column_name>]

Alternatively, you can explicitly specify your states by supplying a hash with the values.

attr_bitwise :<name>, mapping: {<sym1: 1, sym2: 2, sym3: 4>} [, column_name: <column_name>]

Example

You have a website with many locales (English, French, German...) with specific content in each locale. You want your users to be able to chose which content they want to see and you want to be able to query the users by the locales they have chosen.

Start with migration

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      # [...]
      t.integer :locales_value
    end
  end
end

Model

class User < ActiveRecord::Base
  include AttrBitwise

  attr_bitwise :locales, mapping: [:en, :fr, :de]

  scope :with_any_locales, lambda { |*locales_sym|
    where(locales_value: bitwise_union(*locales_sym, 'locales'))
  }

  scope :with_all_locales, lambda { |*locales_sym|
    where(locales_value: bitwise_intersection(*locales_sym, 'locales'))
  }

end

###

# return all users who can see at least english or french content
User.with_any_locales(:en, :fr)

# return all users who can see english and french content
User.with_all_locales(:en, :fr)

API

Examples with name = 'locales'

High level methods

Method	Return	Description
`Class#locales`	`[, ...]`	Return values as symbols
`Class#locales=([value_or_sym, ..])`	`[, ...]`	Given an array of values (Fixnum or Symbol) or single value (Fixnum or Symbol) add them to value.
`Class#locale == fixnum_or_sym`	`Boolean`	Return true if value contains only Fixnum or Symbol
`Class#locale?(fixnum_or_sym)`	`Boolean`	Return true if value contains Fixnum or Symbol
`Class#add_locale(value_or_sym)`	`Fixnum`	Add Fixnum or Symbol to value
`Class#remove_locale(value_or_sym)`	`Fixnum`	Remove Fixnum or Symbol to value
`Class#locales_union([value_or_sym, ..])`	`[Fixnum, ..]`	Given an array of values (Fixnum or Symbol), return bitwise union computation Return all possible values (mask) for an union of given values
`Class#locales_intersection([value_or_sym, ..])`	`[Fixnum, ..]`	Given an array of values (Fixnum or Symbol), return bitwise intersection computation Return all possible values (mask) for an intersection of given values
`Class::LOCALES_MAPPING`	`Hash`	Return `Symbol` -> `Fixnum` mapping

Low level methods

Theses methods are static, so a name parameters is mandatory in order to fetch mapping

Method	Return	Description
`Class.to_bitwise_values(object, name)`	`[Fixnum, ...]`	Given an Object and a attribute name, return Fixnum value depending on mapping
`Class.bitwise_union([Fixnum, ..], name)`	`[Fixnum, ..]`	Given an array of values (Fixnum or Symbol) and a attribute name, return bitwise union computation Return all possible values (mask) for an union of given values
`Class.bitwise_intersection([Fixnum, ..], name)`	`[Fixnum, ..]`	Given an array of values (Fixnum or Symbol) and a attribute name, return bitwise intersection computation Return all possible values (mask) for an intersection of given values

Maintainers : @wittydeveloper and @FSevaistre

kmanzana/attr_bitwise

attr_bitwise