enum_field¶ ↑

• github.com/paraseba/enum_field

Enables Active Record attributes to point to enum like objects, by saving in your database only an integer ID.

• Allows creation of Classes with enum like behaviour.

• Allows any number of members and methods in the enum classes.

• Allows an integer id to be used in your database columns to link to the enum members (user.role_id)

• Enables higher abstraction interaction with AR attributes:

  • user.role = Role.admin

  • if user.role.can_edit?

• Saves in your AR tables, only an integer id pointing to the enumeration member.

When in an Active Record class, you have an attribute like role, state or country you have several options.

• You can create a roles, states or countries table, and dump there all possible values.

• You can use a string to identify, for instance, the role.

• You can use an id to identify the role.

If you are not confortable with any of this options, maybe enum_field is an answer for you.

class Role
  define_enum do |builder|
    builder.member :admin
    builder.member :manager
    builder.member :employee
  end
end

class User < ActiveRecord::Base
  # in the database table there is a role_id integer column
  enumerated_attribute :role
end

link_to_if(current_user.role == Role.admin, edit_foo_path(@foo))

user.role = Role.manager
user.role_id == Role.manager.id  #will be true

User.first.role.id == User.first.role_id  #will be true

Your enum classes can have all the methods you need:

class PhoneType
  def initialize(name)
    @name = name
  end
  attr_reader :name

  define_enum do |b|
    b.member :home,       :object => PhoneType.new('home')
    b.member :commercial, :object => PhoneType.new('commercial')
    b.member :mobile,     :object => PhoneType.new('mobile')
  end
end

user.phone.type.name

You have some AR like methods in enum classes

PhoneType.all == [PhoneType.home, PhoneType.commercial, PhoneType.mobile]  # ordered all
PhoneType.first == PhoneType.home
PhoneType.last == PhoneType.mobile

PhoneType.find_by_id(PhoneType.home.id) == PhoneType.home
PhoneType.find_by_id(123456) == nil
PhoneType.find(2) == PhoneType.commercial
PhoneType.find(123456)  # will raise

The library also mimics has_many :through behavior, for cases such as:

class Role
  define_enum do |builder|
    builder.member :admin
    builder.member :manager
    builder.member :employee
  end
end

class User
  has_many_enumerated_attributes :roles, :through  => UserRole
end

class UserRole < ActiveRecord::Base
  belongs_to :user
  enumerated_attribute :role
end

user = User.create
user.role = [Role.manager, Role.admin]
user.roles.include?(Role.admin)         #will be true
user.roles.include?(Role.manager)       #will be true
user.roles.include?(Role.employee)      #will be false
user.role_ids.include?(Role.manager.id) #will be true
user.role_ids = [Role.employee.id]
user.roles.include?(Role.employee)      #will be true
user.roles.include?(Role.admin)         #will be false

• activerecord

sudo gem install enum_field

(The MIT License)

Copyright © 2009 Sebastián Bernardo Galkin

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.