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Active Model – model interfaces for Rails

Active Model provides a known set of interfaces for usage in model classes. They allow for Action Pack helpers to interact with non-Active Record models, for example. Active Model also helps with building custom ORMs for use outside of the Rails framework.

You can read more about Active Model in the Active Model Basics guide.

Prior to Rails 3.0, if a plugin or gem developer wanted to have an object interact with Action Pack helpers, it was required to either copy chunks of code from Rails, or monkey patch entire helpers to make them handle objects that did not exactly conform to the Active Record interface. This would result in code duplication and fragile applications that broke on upgrades. Active Model solves this by defining an explicit API. You can read more about the API in ::ActiveModel::Lint::Tests.

Active Model provides a default module that implements the basic API required to integrate with Action Pack out of the box: ::ActiveModel::Model.

class Person
  include ActiveModel::Model

  attr_accessor :name, :age
  validates_presence_of :name
end

person = Person.new(name: 'bob', age: '18')
person.name   # => 'bob'
person.age    # => '18'
person.valid? # => true

It includes model name introspections, conversions, translations and validations, resulting in a class suitable to be used with Action Pack. See ::ActiveModel::Model for more examples.

Active Model also provides the following functionality to have ORM-like behavior out of the box:

Download and installation

The latest version of Active Model can be installed with RubyGems:

$ gem install activemodel

Source code can be downloaded as part of the Rails project on GitHub

License

Active Model is released under the MIT license:

Support

API documentation is at:

Bug reports for the Ruby on Rails project can be filed here:

Feature requests should be discussed on the rails-core mailing list here: