Yaml Enumeration

Create classes which work (a bit) like ActiveRecord classes, but are defined as fixed enumerations based on YAML files.

Add this line to your application's Gemfile:

gem 'yaml_enumeration'

And then execute:

$ bundle

Or install it yourself as:

$ gem install yaml_enumeration

Let's assume you have a User class representing a user who can log into your app. This user is supposed to have a home country, and you want to do things like

user = User.new(country: Country.find_by_code('nz'))
puts user.country.code
# => 'nz'
puts user.country.name
# => 'New Zealand'

You can then simply create a Country class:

# country.rb
class Country < YamlEnumeration::Enumeration
  # imports the definitions from the yaml file countries.yml
  load_values :countries

  # all, where, find_by and find_by_type are provided
  def self.find_by_code(code)
    all.find_by(code: code)
  end
end

a yaml file containing all your countries:

# countries.yml
---
nz:
  id: 1 # has to be provided
  type: new_zealand # has to be provided
  name: New Zealand
  code: nz
au:
  id: 2
  type: australia
  name: Australia
  code: au
...

and link that into your User class:

# user.rb
class User < ActiveRecord::Base
  belongs_to_enumeration :country
end

additional yaml syntax such as anchors can be removed from the enumeration by including _exclude_from_enumeration:

# countries.yml
---
defaults_exclude_from_enumeration: &defaults
  continent: Australia

nz:
  <<: *defaults
  id: 1 # has to be provided
  type: new_zealand # has to be provided
  name: New Zealand
  code: nz
au:
  <<: *defaults
  id: 2
  type: australia
  name: Australia
  code: au
uk:
  <<: *defaults
  id: 3
  type: united_kingdom
  name: United Kingdom
  code: uk
  continent: Europe
...

If you include a call to class method with_named_items you will get an item defined for each typed entry in the enumeration, e.g. Country.NEW_ZEALAND and Country.AUSTRALIA.

By passing a column name, e.g:

with_named_items(:code)

that column will be used, e.g: Country.AU and Country.NZ

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/alto/yaml_enumeration. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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