Example from Fearless Rails Controller Refactoring using Dry::GetterInject. See https://gist.github.com/wojtha/b9730d108625e04a0642

create_product_getter_inject.rb

# rewritten example by using container and autoinject

require 'dry-container'

module MyApp
  container = Dry::Container.new
  container.register(:metrics_adapter, -> { MetricsAdapter.new(container[:metrics_configuration]) } )
  container.register(:metrics_configuration, -> { METRICS_CONFIG.fetch(Rails.env) })
  container.register(:create_product_service, -> { CreateProductService.new(container[:metrics_adapter]) })

  AutoInject = Dry::GetterInject(container, :private)

  def self.Inject(*keys)
    AutoInject[*keys]
  end
end

class ProductsController
  include MyApp::Inject(:create_product_service)

  def create
    product = create_product_service.(params[:product])
    redirect_to product_path(product), notice: "Product created"
  rescue CreateProductService::Failed => failure
    # ... probably render ... 
  end
end

create_product_getter_inject_adapter.rb

# rewritten example by using Rails configuration container and autoinject
require 'delegate'

# Rails configuration
MyApp::Application.configure do |config|
  config.metrics_adapter = -> { MetricsAdapter.new(Rails.configuration.metrics_configuration) }
  config.metrics_configuration = -> { METRICS_CONFIG.fetch(Rails.env) }
  config.create_product_service = -> { CreateProductService.new(Rails.configuration.metrics_adapter) }
end

module MyApp
  # We can use adapter or monkeypatch Rails::Application::Configuration
  # Handle only simple keys. Throws NoMethodError.
  class RailsContaineDecorator < SimpleDelegator
    def [](key)
      __getobj__.public_send(key)
    end
  end
  
  # Use Rails.configuration as DI container
  container = RailsContainerDecorator.new(Rails.configuration)
  AutoInject = Dry::GetterInject(container, :private)

  def self.Inject(*keys)
    AutoInject[*keys]
  end
end

class ProductsController
  include MyApp::Inject(:create_product_service)

  def create
    product = create_product_service.(params[:product])
    redirect_to product_path(product), notice: "Product created"
  rescue CreateProductService::Failed => failure
    # ... probably render ... 
  end
end

create_product_service_injector.rb

# original example from chapter Instantiating service objects

module CreateProductServiceInjector
  def metrics_adapter
    @metrics_adapter ||= MetricsAdapter.new(METRICS_CONFIG.fetch(Rails.env))
  end
  
  def create_product_service
    @create_product_service ||= CreateProductService.new(metrics_adapter)
  end
end 

class ProductsController
  include CreateProductServiceInjector
  
  def create
    product = create_product_service.call(params[:product])
    redirect_to product_path (product), notice: "Product created"
  rescue CreateProductService::Failed => failure
    # ... probably render ... 
  end
end