ActiveModel::Type::Symbol

Symbols! They're awesome! Sadly, converting an attribute from a string to a symbol and vice versa by hand is annoying, and validations don't quite work the way you expect without type casting; which can result in hackneyed workarounds like def field=value; super(value.to_sym); end; and def field; super&.to_sym; end;

ActiveRecord 5 introduces the concept of type casting for attributes; which beyond being a great way to leverage composition in your models; also allows us to use symbols more fluidly!

Unfortunately, ActiveModel::Type (the default set of type converters) doesn't include Symbol by default, so I'm tossing one up here so we can all party hardy together until they slurp this code right on up into their codebase.

Installation

Add this line to your application's Gemfile:

gem 'activemodel_type_symbol'

And then execute:

$ bundle

Or install it yourself as:

$ gem install activemodel_type_symbol

Usage

Just... Hanging Out In The Ruby World

ActiveModel::Type::Symbol.new.cast("value") # => :value

In an ActiveRecord model

class YourFancyModel < ApplicationRecord
  validates_inclusion_of :some_field, in: %i(one two three)
  attribute :some_field, :symbol
end


model = YourFancyModel.new(some_field: "one")
model.some_field # => :one
model.valid?     # => true

FAQ

Your first example is basically to_sym but longer

That's not a question. But yes, this safely wraps to_sym so that downstream consumers of ActiveModel can use ActiveModel::Type.lookup(:symbol) to do conversions.

Wait so this needs ActiveRecord?

Teeeccchnnicalllyyyyyy, no. ActiveModel::Type is theoretically generically useable!

Why are you appending things to ActiveModel's namespace?

Because I'm gonna submit this as a patch, but wanted to make it generally available before hand so people aren't forced to upgrade to get that sweet sweet ActiveModel::Type::Symboly goodness

Did you literally spend more time writing the README than you did the code?

NO. Uhh... I mean... Yes.......

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/[USERNAME]/activemodel_type_symbol. 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.

License

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

Code of Conduct

Everyone interacting in the ActiveModel::Type::Symbol project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.