Question

I am installing a gem called completeness-fu.

This is the error I get:

completeness-fu-0.6.0/lib/completeness-fu/active_model_additions.rb:12:in `define_completeness_scoring': please make sure ActiveModel::Naming is included so completeness_scoring can translate messages correctly (CompletenessFu::CompletenessFuError)

What does that mean?

Answer 1

ActiveModel::Naming creates a #model_name method on your object. The completeness-fu gem seems to require it for the #define_completeness_scoring method.

From the readme:

Completeness-Fu used to be for ActiveRecord only, but this has changed with the latest version with only ActiveModel needed as a gem dependency (and a little ActiveSupport). This means that the latest version works with the following ORMs :

• ActiveRecord
• Mongoid
• Cassandra Object

The define_completeness_scoring method is mixed into the above mentioned ORMs by default, but if you want to use Completeness-Fu in an ActiveModel model which isn’t one of the above ORMs, make sure you include ActiveModel::Naming. If you want to cache the completeness score make sure you also include ActiveModel::Validations and ActiveModel::Validations::Callbacks.

Updated

See comments; the underlying issue seems to be a bug in the gem (as of 29 June, 2011). This could be monkey-patched using the following code (assuming Ruby 1.9). The only change is using self.singleton_class.include?(ActiveModel::Naming) to get the proper response.

# lib/completeness-fu.rb
module CompletenessFu
  module ActiveModelAdditions
    def self.included(base)
      base.class_eval do
        def self.define_completeness_scoring(&checks_block)
          # The check below is causing the problem; the simplest fix in Ruby 1.8
          # would be to simply remove it by commenting out the following 3 lines.
          unless self.singleton_class.include?(ActiveModel::Naming)
            raise CompletenessFuError, 'please make sure ActiveModel::Naming is included so completeness_scoring can translate messages correctly'
          end

          class_inheritable_array :completeness_checks
          cattr_accessor :default_weighting
          cattr_accessor :model_weightings

          self.send :extend, ClassMethods
          self.send :include, InstanceMethods

          checks_results = CompletenessFu::ScoringBuilder.generate(self, &checks_block)

          self.default_weighting   = checks_results[:default_weighting]
          self.completeness_checks = checks_results[:completeness_checks]
          self.model_weightings    = checks_results[:model_weightings]

          if checks_results[:cache_score_details]
            unless self.include?(ActiveModel::Validations::Callbacks)
              raise CompletenessFuError, 'please make sure ActiveModel::Validations::Callbacks is included before define_completeness_scoring if you want to cache competeness scoring'
            end
            self.before_validation checks_results[:cache_score_details]
          end
        end
      end
    end
  end
end

Warning!!!

This is a super temporary (and fragile) monkey-patch, and I really don’t recommend actually using code like this in a production capacity.

The better options would be to find a different gem for this, work with the author to get it fixed, fork the project and fix it yourself then use that fork in your project (more info) or simply rebuild this functionality in your app locally using the gem as a starting design.