ActiveType

Make any Ruby object quack like ActiveRecord

ActiveType is our take on "presenter models" (or "form models") in Rails. We want to have controllers (and forms) talk to models that are either not backed by a database table, or have additional functionality that should not be shared to the rest of the application.

However, we do not want to lose ActiveRecord's amenities, like validations, callbacks, etc.

Examples for use cases are models to support sign in:

class SignIn < ActiveType::Object

  # this is not backed by a db table

  attribute :username, :string
  attribute :password, :string

  validates :username, presence: true
  validates :password, presence: true

  # ...

end

Or models to support sign up:

class User < ActiveRecord::Base
  # ...
end

class SignUp < ActiveType::Record[User]

  # this inherits from User

  validates :password, confirmation: true

  after_create :send_confirmation_email

  def send_confirmation_email
    # this should happen on sign-up, but not when creating a user in tests etc.
  end

  # ...

end

ActiveType::Object

Inherit from ActiveType::Object if you want an ActiveRecord-kind class that is not backed by a database table.

You can define "columns" by saying attribute:

class SignIn < ActiveType::Object

  attribute :email, :string
  attribute :date_of_birth, :date
  attribute :accepted_terms, :boolean

end

These attributes can be assigned via constructor, mass-assignment, and are automatically typecast:

sign_in = SignIn.new(date_of_birth: "1980-01-01", accepted_terms: "1")
sign_in.date_of_birth.class # Date
sign_in.accepted_terms # true

ActiveType::Object actually inherits from ActiveRecord::Base, but simply skips all database access, inspired by ActiveRecord Tableless.

This means your object has all usual ActiveRecord::Base methods. Some of those might not work properly, however. What does work:

• validations
• callbacks (use before_save, after_save, not before_create, or before_update)
• "saving" (returning true or false, without actually persisting)
• belongs_to (after saying attribute :child_id, :integer)

ActiveType::Record

ActiveType::Record is simply ActiveRecord::Base plus the (virtual) attributes from ActiveType::Object. You can declare, assign, validate etc those attributes, but they will not be persisted.

ActiveType::Record[BaseClass]

ActiveType::Record[BaseClass] is used to extend a given BaseClass (that itself has to be an ActiveRecord model) with additional functionality, that is not meant to be shared to the rest of the application.

You class will inherit from BaseClass. You can add additional methods, validations, callbacks, as well as use (virtual) attributes like an ActiveType::Object:

class SignUp < ActiveType::Record[User]
  # ...
end

Supported Rails versions

ActiveType is tested against ActiveRecord 3.2, 4.0 and 4.1.

Later versions might work, earlier version will not.

Installation

In your Gemfile say:

gem 'active_type'

Now run bundle install and restart your server.

Development

• We run tests against several ActiveRecord versions.
• You can bundle all versions with rake all:bundle.
• You can run specs against all versions with rake.
• You can run specs against a single version with VERSION=4.0 rake.

If you would like to contribute:

• Fork the repository.
• Push your changes with passing specs.
• Send us a pull request.

I'm very eager to keep this gem leightweight and on topic. If you're unsure whether a change would make it into the gem, talk to me beforehand.

Credits

Tobias Kraze from makandra

Henning Koch from makandra