DRY-ing up service logic with mixins. Since these services are very similar in behavior I used a "template" method that uses only one dynamic data: the entity type they are fetching.

loads_position_types.rb

module Services
  class LoadsPositionTypes
    extend ::Services::LookupDataFetchable

    def self.entity_class
      PositionType
    end

  end
end

loads_states.rb

module Services
  class LoadsStates
    extend ::Services::LookupDataFetchable

    def self.entity_class
      State
    end

  end
end

lookup_data_fetchable.rb

module Services
  module LookupDataFetchable
    def entity_class
      raise NotImplementedError.new("You must implement the class method `entity_class`")
    end

    def from_api(current_user)
      service = Object::const_get("Services").const_get("Api").const_get(entity_class.to_s.pluralize) \
                        .new(current_user.email, current_user.password)

      data_json_array = Rails.cache.fetch(entity_class.to_s.downcase.to_sym) do
        service.index.fetch("entries")
      end

      data_json_array.map do |e|
        entity_class.new(e)
      end
    end
  end
end

class String
  def to_class
    self.split("::").reduce(Object) { |o, part| o.const_get part }
  end
end

Then line 8 becomes:

service = "Services::Api::#{entity_class.to_s.pluralize}".to_class.new(current_user.email, current_user.password)

Not much of an improvement, but I like to extend String to do that 😄

I would consider calling "to_class" "constantize" just to make Rails developers feel more at home :)