array_enum

ArrayEnum

Extension for ActiveRecord that adds support for PostgreSQL array columns, mapping string values to integers.

Installation

gem install array_enum or use Gemfile with bundler

Usage

ActiveRecord extension

Database will store integers that after reading will map to string values.

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.integer :favourite_colors, array: true, null: false, default: []
  end
end

class User < ActiveRecord::Base
  extend ArrayEnum

  array_enum favourite_colors: {"red" => 1, "blue" => 2, "green" => 3}
end

user = User.create!(favourite_colors: ["red", "green"])
user.favourite_colors # => ["red", "green"]
User.favourite_colors # => {"red" => 1, "blue" => 2, "green" => 3}

Several scopes are made available on your model to find records based on a value or an array of values:

user1 = User.create!(favourite_colors: ["red", "green"])
user2 = User.create!(favourite_colors: ["red"])

# Find a record that has _all_ the provided values in the array enum attribute
User.with_favourite_colors("red") # => [user1, user2]
User.with_favourite_colors(%w[red green]) # => [user1]
User.with_favourite_colors(%w[red blue]) # => []
User.with_favourite_colors(%w[green blue]) # => []

# Find a record that has the provided values, and _only those values_, in the array enum attribute
User.only_with_favourite_colors("red") # => [user2]
User.only_with_favourite_colors(%w[red green]) # => [user1]
User.only_with_favourite_colors(%w[red blue]) # => []
User.only_with_favourite_colors(%w[green blue]) # => []

# Find a record that has _at least one_ of the provided values in the array enum attribute
User.with_any_of_favourite_colors("red") # => [user1, user2]
User.with_any_of_favourite_colors(%w[red green]) # => [user1, user2]
User.with_any_of_favourite_colors(%w[red blue]) # => [user1, user2]
User.with_any_of_favourite_colors(%w[green blue]) # => [user1]

Attempting to find a record with a value that is not in the enum will fail:

User.with_favourite_colors("yellow") # => ArgumentError["yellow is not a valid value for favourite_colors"]

Subset Validator

Additionally subset validator is provided that can help to ensure correct values are passed during validation.

class CreateUser
  include ActiveModel::Model

  attr_accessor :favourite_colors

  validates :favourite_colors, subset: ["green", "blue"]
  # or:
  # validates :favourite_colors, subset: { in: ->(record) { Color.pluck(:name) } }
end

CreateUser.new(favourite_colors: ["black"]).valid? # => false

Development

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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/freeletics/array_enum.

License

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