MagicEnum is a simple ActiveRecord plugin that makes it easier to maintain ENUM-like attributes in your models.

Examples:

Statuses = {
  :draft => 0,
  :published => 1,
  :approved => 2
}
define_enum :status

Before using define_enum, you should define constant with ENUM options. Constant name would be pluralized enum attribute name. Additional constant named like YourEnumInverted would be created automatically and would contain inverted hash.

Please note: nil and 0 are not the same values!

You could specify additional options:

• :default - value which will be used when current state of ENUM attribute is invalid or wrong value received. If it has not been specified, min value of the ENUM would be used.

• :raise_on_invalid - if true an exception would be raised on invalid enum value received. If it is false, default value would be used instead of wrong one.

• :simple_accessors - if true, additional methods for each ENUM value would be defined in form value?. Methods returns true when ENUM attribute has corresponding value.

• :enum - string with name of the ENUM hash.

Look the following example:

Statuses = {
  :unknown => 0,
  :draft => 1,
  :published => 2,
  :approved => 3
}
define_enum :status, :default => 1, :raise_on_invalid => true, :simple_accessors => true

This example is identical to:

Statuses = {
  :unknown => 0,
  :draft => 1,
  :published => 2,
  :approved => 3
}
StatusesInverted = Statuses.invert

def status
  return StatusesInverted[self[:status].to_i] || StatusesInverted[1]
end

def status=(value)
  raise ArgumentError, "Invalid value \"#{value}\" for :status attribute of the #{self.class} model" if Statuses[value].nil?
  self[:status] = Statuses[value]
end

def unknown?
  status == :unknown
end

def draft?
  status == :draft
end

def published?
  status == :published
end

def approved?
  status == :approved
end

This plugin was originally developed for BestTechVideos project (www.bestechvideos.com) by Dmytro Shteflyuk (kpumuk.info) and later cleaned up in Scribd repository and released to the public by Oleksiy Kovyrin. All the code in this package is released under the MIT license. For more details, see the LICENSE file.