Tainbox

Tainbox is a utility gem that can be used to inject attributes into Ruby objects. It is similar to Virtus, but works a bit more sensibly (hopefully) and throws in some additional features.

But we already have attr_accessor!

Consider this code:

class Person
  include Tainbox
  attribute :name, default: -> { "person_#{age}" }
  attribute :age, Integer, default: 20
end

Here are the basic features you get:

person = Person.new(name: 'John', age: '30')
person.attributes # => { :name => "John", :age => 30 }
person.age = 50
person.age # => 50
person.attributes = {}
person.attributes # => { :name => "person_20", :age => 20 }

NOTE: There are two ways to change attributes in bulk. attributes= replaces missing values with nils or default values, while patch_attributes leaves missing attributes untouched.

But what's wrong with Virtus?

Observe:

class Person
  include Virtus::Model
  attribute :age, Integer
end

Person.new(age: 'invalid_integer').age # => "invalid_integer"

Additional features

Method overrides

Tainbox attributes can be freely overriden:

def name
  super.strip
end

def name=(value)
  super('Stupid example')
end

#attribute_provided?

Attribute is considered provided if its setter was explicitly invoked via a setter, .new, or #attributes= or it has a default value.

class Person
  include Tainbox
  attribute :name, default: 'John'
  attribute :age
end

person = Person.new
person.attribute_provided?(:age) # => false
person.attribute_provided?(:name) # => true

Disabling automatic attribute readers and writers

Speaks for itself:

class Person
  include Tainbox
  attribute :name, reader: false
  attribute :age, writer: false
end

Built-in type converters

All converters return nil if conversion could not be made.

• Integer
• Float
• String
• Symbol
• Time
• Boolean

String type converter options

String converter supports additional options: strip and downcase which strip and downcase input attribute values respectively

Example:

attribute :name, String, strip: true, downcase: true

Custom type converters

You can define a custom type converter like so:

# value and options are automatically available in scope
Tainbox.define_converter(MyType) do
  # Do whatever you want with value
  options[:strict] ? MyType.convert!(value) : MyType.convert(value)
end

as_json

class Person
  include Tainbox
  attribute :name
  attribute :age
end

person = Person.new(name: 'John', age: 20)

person.as_json                # => { 'name' => 'John', 'age' => 20 }
person.as_json(only: :name)   # => { 'name' => 'John' }
person.as_json(except: :name) # => { 'age' => 20 }

Suppressing tainbox initializer

If you don't want to pollute your class with tainbox initializer you can do:

class Person
  include Tainbox
  suppress_tainbox_initializer!
end