Decorators Presenters and Commands in Ruby on Rails

🚀 Mastering Decorators, Presenters, and Commands in Ruby on Rails

Ruby on Rails (RoR) is a framework that thrives on clean and maintainable code. But have you ever wondered how to better separate concerns, handle presentation logic, or encapsulate business logic efficiently? Today, we dive into Decorators, Presenters, and Commands — powerful patterns that will elevate your Rails applications! 🌟

🎭 Decorators: Adding Behavior without Changing Objects

A Decorator is used to add extra behavior to an object dynamically, without modifying its original class. It’s particularly useful for organizing view-related logic.

Example:

# app/decorators/user_decorator.rb
class UserDecorator < SimpleDelegator
  def full_name
    "#{first_name} #{last_name}"
  end

  def formatted_join_date
    created_at.strftime("%B %d, %Y")
  end
end

# Usage in Controller
@user = User.find(params[:id])
@decorated_user = UserDecorator.new(@user)

Hack:

• Use the Draper gem for a more streamlined approach to creating decorators. It integrates seamlessly with Rails:

# Gemfile
gem 'draper'

class UserDecorator < Draper::Decorator
  delegate_all

  def display_name
    object.name.upcase
  end
end

# Usage
@user = User.find(params[:id]).decorate

Best Use:

• View-specific logic like formatting dates, names, or conditional display content.

🎨 Presenters: Focus on Presentation Layer

Presenters are similar to Decorators but with a specific focus on enhancing the presentation logic. They act as a middle layer between your models and views, often combining multiple models into one cohesive interface.

Example:

# app/presenters/order_presenter.rb
class OrderPresenter
  def initialize(order)
    @order = order
  end

  def total_price
    @order.items.sum(&:price) + shipping_cost
  end

  def shipping_cost
    @order.expedited? ? 10 : 5
  end
end

# Usage in Controller
@order = Order.find(params[:id])
@presenter = OrderPresenter.new(@order)

Hack:

• Use the view_context in your Presenter for direct access to Rails helpers, making it even more flexible:

def formatted_total_price
  view_context.number_to_currency(total_price)
end

Best Use:

• When you need to abstract complex presentation logic from the view.

🛠️ Commands: Encapsulate Business Logic

The Command pattern encapsulates a business operation in a single class, making it reusable, testable, and easy to maintain. Commands are ideal for performing tasks that might otherwise clutter your models or controllers.

Example:

# app/commands/create_order_command.rb
class CreateOrderCommand
  def initialize(user, cart)
    @user = user
    @cart = cart
  end

  def execute
    Order.create!(user: @user, total_price: @cart.total_price)
  end
end

# Usage in Controller
command = CreateOrderCommand.new(current_user, current_cart)
@order = command.execute

Hack:

• Chain commands together for workflows using a service object:

# app/services/order_service.rb
class OrderService
  def initialize(user, cart)
    @user = user
    @cart = cart
  end

  def place_order
    command = CreateOrderCommand.new(@user, @cart)
    notify_user(command.execute)
  end

  private

  def notify_user(order)
    UserMailer.order_confirmation(order).deliver_later
  end
end

Best Use:

• Encapsulating domain logic that doesn’t belong in controllers or models, like workflows or API interactions.

⚡ Quick Hacks for Efficient Usage

1. Use Decorators for enhancing objects with reusable, view-specific methods.
2. Leverage Presenters when combining data from multiple models into a single, clean interface for views.
3. Apply Commands to separate complex operations from models and controllers.
4. Naming Matters — Choose meaningful names for Decorators, Presenters, and Commands to clearly indicate their purpose.
5. Testing Made Easy — Since these patterns separate concerns, they’re easier to unit test individually. 🧪

🌟 Conclusion

By integrating Decorators, Presenters, and Commands into your Ruby on Rails projects, you’ll write cleaner, more maintainable code. These patterns help you stay organized, improve testability, and keep your application logic decoupled. 🚀

What are your favorite patterns in Rails? Let us know in the comments! ✨