SmartAdapters

Smart Adapters neatly decouple the controllers from the views independently by the request format. In the Ruby on Rails documentation, the controller decides the format of the answer based on the (Content-Type) request:

# app/controllers/people_controller.rb
def index
  @people = Person.all
  respond_to do |format|
    format.html
    format.xml { render :xml => @people.to_xml }
  end
end

The problem here is that over time the controllers inherit unnecessary complexity due to the evolution of the project (new logics and/or formats). The Smart Adapters solve the problem responding to a request with the appropriate format by using purposely designed classes.

# Controller
# app/controllers/people_controller.rb
def index
  current_adapter.success Person.all
end

# HTML Adapter
# app/models/smart_adapters/people/index/html_adapter.rb
def success(people)
  render 'people/show', locals: { people: people }
end

# XML Adapter
# app/models/smart_adapters/people/index/xml_adapter.rb
def success(people)
  render xml: people, status: :ok
end

The application can now be kept dry while introducing new formats and functionalities. For instance, in case of an XML request, the adapter could add more details to the people collection or track some metrics without bloating the controller.

# app/models/smart_adapters/people/index/xml_adapter.rb
def success(people)
  metric_tracker.push('New XML request')
  people.filter_private_details!
  render xml: people, status: :ok
end

Installation

Add this line to your application's Gemfile:

gem 'smart_adapters'

And then execute:

$ bundle

Update the ApplicationController by adding the SmartAdapters concern:

class ApplicationController < ActionController::Base
  include SmartAdapters
end

Add the adapters for your controller/action/format.

Formats supported

• HTML
• JSON
• JS
• XML
• CSV
• TXT

Example

app/controlles/users_controller.rb

class UsersController < ApplicationController
  # GET /users
  def index
    current_adapter.success User.all
  end

  # GET /users/1
  def show
    if user
      current_adapter.success(user)
    else
      current_adapter.failure(user)
    end
  end

  # PATCH/PUT /users/1
  def update
    if user.update_attributes(update_params)
      current_adapter.success(user)
    else
      current_adapter.failure(user)
    end
  end

  private

  def update_params
    params.require(:user).permit(:first_name, :last_name)
  end

  def user
    @user ||= User.find_by(id: params[:id])
  end
end

app/models/smart_adapters/users/index/html_adapter.rb

module SmartAdapters
  module Users
    module Index
      class HtmlAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Html::Default

        def success(resource)
          render 'users/show', locals: { resource: resource }
        end
      end
    end
  end
end

app/models/smart_adapters/users/index/json_adapter.rb

module SmartAdapters
  module Users
    module Index
      class JsonAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Json::Default

        def success(resource)
          render json: resource, status: :ok
        end
      end
    end
  end
end

app/models/smart_adapters/users/show/html_adapter.rb

module SmartAdapters
  module Users
    module Show
      class HtmlAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Html::Default

        def success(resource)
          render 'objects/show', locals: { resource: resource }
        end

        def failure(resource)
          redirect_back fallback_location: root_path, flash: { error: 'Resource not found' }
        end
      end
    end
  end
end

app/models/smart_adapters/users/show/json_adapter.rb

module SmartAdapters
  module Users
    module Show
      class JsonAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Json::Default

        def success(resource)
          render json: resource, status: :ok
        end

        def failure(resource)
          render json: {}, status: :not_found
        end
      end
    end
  end
end

app/models/smart_adapters/users/update/html_adapter.rb

module SmartAdapters
  module Users
    module Update
      class HtmlAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Html::Default

        def success(resource)
          render 'objects/show', locals: { resource: resource }
        end

        def failure(resource)
          unless resource.present?
            return redirect_back fallback_location: root_path, flash: { error: 'Resource not found' }
          end
          redirect_back fallback_location: root_path, flash: { error: resource.errors }
        end
      end
    end
  end
end

app/models/smart_adapters/users/update/json_adapter.rb

module SmartAdapters
  module Users
    module Update
      class JsonAdapter < SimpleDelegator
        include SmartAdapters::Util::Adapters::Json::Default

        def success(resource)
          render json: resource, status: :ok
        end

        def failure(resource)
          return render json: {}, status: :not_found unless resource.present?
          render json: { errors: resource.errors }, status: :bad_request
        end
      end
    end
  end
end

TODO

• Add remaining formats: ~~:text~~, :ics, ~~:csv~~, :yaml, :rss, :atom
• Add generator