Define enum classes in Rails and use them to enumerate ActiveRecord attributes. Brings together some ideas of similar plugins that I liked and does it they way I prefer.
Enum values are stored in memory at the moment but I plan to add database and possibly others. See Storage Backends.
From version 0.7 onwards this plugin will only have Rails 3 support. If you need Rails 2 compatibility, check the 0.6 branch.
gem install active_enum
Put this in your Gemfile
gem 'active_enum'
Then generate the config initializer file
rails generate active_enum:install
Define an enum class with values
class Sex < ActiveEnum::Base value :id => 1, :name => 'Male' value :id => 2, :name => 'Female' end
Define with id as the key
class Sex < ActiveEnum::Base value 1 => 'Male' value 2 => 'Female' end
Define using implicit id values
class Sex < ActiveEnum::Base value :name => 'Male' value :name => 'Female' end
Beware that if you change the order of values defined in an enum which don’t have explicit ids, then the ids will change. This could corrupt your data if the enum values have been stored in a model record, as they will no longer map to the original enum.
Define values with meta data
class Sex < ActiveEnum::Base value :id => 1, :name => 'Male', :symbol => '♂' value :id => 2, :name => 'Female', :symbol => '♀' end
The meta data can be any other key-value pairs, it’s not limited to certain keys.
Enum class usage
Sex[1] # => 'Male' Sex['Male'] # => 1 Sex[:male] # => 1 Sex.meta(1) # => { :symbol => '♂' } Sex.to_select # => [['Male', 1], ['Female',2]] for select form helpers
To define the sorting of returned values use the order method. Which is useful for to_select method.
class Sex < ActiveEnum::Base order :asc value :id => 1, :name => 'Male' value :id => 2, :name => 'Female' end
By default the order is ascending (:asc) but you can also choose descending (:desc) or in natural order of definition (:natural). The last option is useful when supplying id values but have a specific order needed to display them.
Use the enum to enumerate an ActiveRecord model attribute
class User < ActiveRecord::Base enumerate :sex, :with => Sex end
Skip the with option if the enum can be implied from the attribute
class User < ActiveRecord::Base enumerate :sex end
Define enum class implicitly from enumerate block. Enum class is namespaced by model class.
class User < ActiveRecord::Base # defines User::Sex enum class enumerate :sex do value :name => 'Male' end end
Multiple attributes with same enum
class Patient < ActiveRecord::Base enumerate :to, :from, :with => Sex end
You can use an enum in a validation of inclusion like so
class User < ActiveRecord::Base enumerate :sex, :with => Sex validates_inclusion_of :sex, :in => Sex end
This works because an enum class responds to #include?().
Access the enum values and the enum class using the attribute method with a symbol for the enum component you want
user = User.new user.sex = 1 user.sex # => 1 user.sex(:id) # => 1 user.sex(:name) # => 'Male' user.sex(:enum) # => Sex user.sex(:symbol) # => ♂ ( Can use any meta data key )
You can set the default to return the enum name value for enumerated attribute
ActiveEnum.use_name_as_value = true user.sex # => 'Male'
You can check if the attribute value matches a particular enum value by passing the enum value as an argument to the question method
user.sex?(:male) # => true user.sex?(:Male) # => true user.sex?('Male') # => true user.sex?('Female') # => false
A convenience method on the class is available to the enum class of any enumerated attribute
User.active_enum_for(:sex) # => Sex
Define enum classes in bulk without class files, in an initializer file for example.
ActiveEnum.define do # defines Sex enum(:sex) do value :name => 'Male' value :name => 'Female' end # defines Language enum(:language) do value :name => 'English' value :name => 'German' end end
All defined enum classes are stored in ActiveEnum.enum_classes array if you need look them up or iterate over them.
You can make an existing model class behave like an enum class with acts_as_enum
class Country < ActiveRecord::Base acts_as_enum :name_column => 'short_name' end
Giving you the familiar enum methods
Country[1] Country['Australia'] Country.to_select
There is support for Formtastic and SimpleForm to make it easier to use the enum values as select options. The plugins have an almost identical API which is handy. You just need to require the extension for the respective plugin in an initialiser:
Formtastic 2.x:
require 'active_enum/form_helpers/formtastic2'
Formtastic <2:
require 'active_enum/form_helpers/formtastic'
Or, SimpleForm:
require 'active_enum/form_helpers/simple_form'
The input type will be automatically detected for enumerated attributes. You can override with the :as option as normal.
The design allows pluggable backends to be used for stories and retrieving the enum values. At present there are two available, memory or I18n. To change the storage engine you alter the storage config value like so:
ActiveEnum.setup do |config| config.storage = :i18n end
The memory store is default obviously just stores the values in memory.
The I18n storage backend stores the ids and names is memory still, but retrieves the name text translation any call to the enum public methods.
To set up the locale file, run
rails g active_enum:locale
This generates the YML locale template in your default language as configured in the application.rb.
Here are some examples of defining enum translations
class Sex < ActiveEnum::Base value 1 => 'male' value 2 => 'female' end
becomes
sex: male: Male female: Female
For namesapced enums in a model
class Person < ActiveRecord::Base enumerate :sex do value 1 => 'male' value 2 => 'female' end end
nest the translations under the underscored model name
person:
sex:
male: Male
female: Female
Copyright © 2009 Adam Meehan, released under the MIT license