composable_decorator

ComposableDecorator

A simple, composable decorator for Rails models.

Example

class User < ActiveRecord::Base
  decorate_with NameDecorator, PhoneNumberDecorator
end

@user = User.find(1).decorate
@user.full_name # => "Jane Smith"

Installation

Add this line to your application's Gemfile:

gem 'composable_decorator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install composable_decorator

Usage

Decorators are declared as modules.

module NameDecorator
  def full_name
    "#{first_Name} #{last_name}"
  end
end

A #decorate_with method is called in the model that lists the order of decorators to be added to the instance.

# /app/models/user.rb
class User < ActiveRecord::Base
  decorate_with NameDecorator, PhoneNumberDecorator
end

This is roughly the equivalent of wrapping the instance in first the Name decorator, then the PhoneNumber decorator, i.e.:

class User < ActiveRecord::Base
  extend NameDecorator
  extend PhoneNumberDecorator
end

We can then decorate the model in the controller and access the decorated methods in the view.

# /app/controllers/users_controller.rb
class UsersController
  def show
    ...
    @user.decorate
  end
end

# /app/views/users/show.html.slim
@user.full_name
@user.full_phone_number

Decorators are inherited

module HatDecorator
  def hat_decorated_method
    "hat decorator method"
  end
end

class Hat < ActiveRecord::Base
  decorate_with HatDecorator
end

class Stetson < Hat
end

Stetson.new.decorate.hat_decorator_method #=> "hat decorator method"

Delegating an association's decorated methods

We can delegate the association's decorated methods to the instance all at once.

module AddressDecorator
  def simple_format
    "#{street}, #{city}"
  end
end

class Address < ActiveRecord::Base
  decorate_with AddressDecorator
end

class User
  delegate_decorated_to :address
end

# /app/views/users/show.html.slim
User.find(1).decorate.address_simple_format

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/composable_decorator. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.