Resolve - dry-effects dependency injection

whole_app_dependencies.rb

class ProviderMiddleware
  include Dry::Effects::Handler.Resolve

  def initialize(app, dependencies)
    @app = app
    @dependencies = dependencies
  end

  def call(env)
    provide(@dependencies) { @app.(env) }
  end
end



use ProviderMiddleware, user_repo: UserRepo.new
run Application.new

with.rb

class UserService
  include Dry::Effects.Resolve(:user_repo)
  def get_all_users
    user_repo.get_all
  end
end

class UserRepository
  def get_all
    User.all
  end
end

class UsersController
  include Dry::Effects::Handler.Resolve
  def index
    provide(user_repo: UserRepository.new) do
      users = UserService.new.get_all_users
      render json: users
    end
  end
end

without.rb

class UsersController
  def index
    users = user_service.get_all_users
    render json: users
  end

  private

  def user_service
    @user_service ||= UserService.new(user_repository)
  end

  def user_repository
    @user_repository ||= UserRepository.new
  end
end

class UserService
  def initialize(user_repository)
    @user_repository = user_repository
  end

  def get_all_users
    @user_repository.get_all
  end
end

class UserRepository
  def get_all
    User.all
  end
end