importer.rb

# app/models/importer.rb
class Importer
  include ActiveModel::Validations
  include ActiveModel::Conversion

  VALID_IMPORT_TYPES = ['contact']

  validates :import_type, inclusion: { in: VALID_IMPORT_TYPES }

  attr_reader :parser, :import_type

  def initialize(attributes={})
    @parser = attributes[:parser]
    @import_type = attributes[:import_type]
  end

  def import
    if valid?
      rows.each do |row|
        import_factory.create(row)
      end
    end
  end

  private

  def rows
    parser.rows
  end

  def import_factory
    import_type.to_s.constantize
  end
end

xml_parser.rb

# app/models/xml_parser.rb
class XMLParser
  def initialize(xml_file)
    @xml_file = xml_file
  end

  def rows
    # code that parses the XML file and returns an array of hashes
  end
end