Skip to Content Skip to Search

Active Model ImmutableString Type

Attribute type to represent immutable strings. It casts incoming values to frozen strings.

class Person
  include ActiveModel::Attributes

  attribute :name, :immutable_string
end

person = Person.new
person.name = 1

person.name # => "1"
person.name.frozen? # => true

Values are coerced to strings using their to_s method. Boolean values are treated differently, however: true will be cast to "t" and false will be cast to "f". These strings can be customized when declaring an attribute:

class Person
  include ActiveModel::Attributes

  attribute :active, :immutable_string, true: "aye", false: "nay"
end

person = Person.new
person.active = true

person.active # => "aye"
Methods
N
S
T

Class Public methods

new(**args)

Source: show 

# File activemodel/lib/active_model/type/immutable_string.rb, line 38
def initialize(**args)
  @true  = -(args.delete(:true)&.to_s  || "t")
  @false = -(args.delete(:false)&.to_s || "f")
  super
end

Instance Public methods

serialize(value)

Source: show 

# File activemodel/lib/active_model/type/immutable_string.rb, line 48
def serialize(value)
  case value
  when ::Numeric, ::Symbol, ActiveSupport::Duration then value.to_s
  when true then @true
  when false then @false
  else super
  end
end

type()

Source: show 

# File activemodel/lib/active_model/type/immutable_string.rb, line 44
def type
  :string
end