multi_parameter_attributes.rb

module Mongoid
  module MultiParameterAttributes
    protected

    # Override mongoid / lib / mongoid / multi_parameter_attributes.rb
    def instantiate_object(field, values_with_empty_parameters)
      return nil if values_with_empty_parameters.all? { |v| v.nil? } || !field
      values = values_with_empty_parameters.collect { |v| v.nil? ? 1 : v }
      klass = field.type
      if klass == DateTime || klass == Date || klass == Time
        field.serialize(values)
      elsif klass == String
        klass.new values.join
      elsif klass
        klass.new *values
      else
        values
      end
    end
  end
end