Nummernkreis

This gem implements a number range ("Nummernkreis" in German) which is very common for German documents like invoices where the invoice number is not just a number sequence but also includes date components.

Add this line to your application's Gemfile:

gem 'nummernkreis'

And then execute:

$ bundle

Or install it yourself as:

$ gem install nummernkreis

When generating a new number range you need to specify its pattern. The following components are possible:

  yyyy: year with full 4 digits (e.g. 1980 or 2019)
    yy: year with two digits (e.g. 19 for 2019)
    mm: month starting with 1 (e.g. 02 for February)
    dd: day of the month starting with 1 (e.g. 01 for first day)
    - : dash separator
    # : part of the sequence that will be incremented.

Examples (assuming current date is 2019-04-15):

  Nummernkreis.new('####').to_s
  # '0001'

  nummernkreis = Nummernkreis.new('yymmdd-##')
  nummernkreis.to_s
  # '190425-01'

  nummernkreis.next
  # '190425-02'

  nummernkreis.parse('181231-04')
  nummernkreis.next
  # '181231-05'

  nummernkreis.next(now: true)
  # '190425-01'

  nummernkreis.next
  # '190425-02'

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/frontrunnerio/nummernkreis. You can just use Gitpod and start hacking.

The gem is available as open source under the terms of the MIT License.