import-example.rb

# This is a basic example how to create an import from csv data. This could 
# be called in a rake task:

namespace :db do
  namespace :import do
    desc "Import customer of old shop from csv"
    task :customer => :environment do
      csv_file = 'db/customer_data.csv'
      importer = Import::ImportCustomer.new(IO.read(csv_file))
      importer.import
    end
  end
end

# Here is a basic import module and class and a class for a userImport - this should 
# be placed in two separate files.
# I removed the error handling from the code to concentrate more on the basics. I 
# strongly recommend to add it!

require 'csv'

module Import
  class Importer
    attr_accessor :csv_stream

    def initialize(csv_stream)
      @csv_data = {}
      convert_csv_data(csv_stream)
    end

    def convert_csv_data(csv_stream)
      @csv_data = CSV.new csv_stream, {:headers => true, :col_sep => ','}
      @csv_data.convert do |field, info|
      next if field.blank?
      field.strip
    end
  end
end

module Import
  class ImportCustomer < Importer
    def import
      User.transaction do
        import_customer_data
      end
    end

    def import_customer_data
      @csv_data.each do |row|
        data = row.to_hash
        save_data_to_db(data)
      end
    end

    def save_data_to_db(data)
      data_hash = {
        :email => data['kd_email'] || '',
        :salutation => data['kd_anrede'] || '',
        :first_name => data['kd_vorname'] || '',
        :last_name => data['kd_nachname'] || ''
      }

      user = User.new(data_hash)
      user.save
    end
  end
end