validate_models.rake

desc <<-EOT
Display the id and error messages of all invalid instances of each model in
model_classes, which should be a comma separated list of model names.  If
model_classes is blank all models will be reported.
EOT
task :validate_models, [:models] => :environment do |t, args|
  model_classes = if args[:models]
                    args[:models].split(',').map(&:constantize)
                  else
                    Rails.application.eager_load!
                    ActiveRecord::Base.descendants
                  end
  model_classes.each do |model_class|
    $stderr.puts "# #{model_class.name}"
    model_class.all.reject(&:valid?).each do |model|
      puts "%s:%d:%s" % [model_class.name, model.id, model.errors.full_messages]
    end
  end
end