grape_sorbet is a gem that provides hand written signatures and a Tapioca DSL compiler that makes it more pleasant to use the Grape API framework in Ruby projects that use the Sorbet typechecker.

Install the gem and add to the application's Gemfile by executing:

$ bundle add grape_sorbet

If bundler is not being used to manage dependencies, install the gem by executing:

$ gem install grape_sorbet

After installing the gem, make sure to run bundle exec tapioca gem grape_sorbet in your project to import the hand written signatures.

Starting with the following example from grape's documentation:

module Twitter
  class API < Grape::API
    version 'v1', using: :header, vendor: 'twitter'
    format :json
    prefix :api

    helpers do
      def current_user
        @current_user ||= User.authorize!(env)
      end

      def authenticate!
        error!('401 Unauthorized', 401) unless current_user
      end
    end

    resource :statuses do
      desc 'Return a personal timeline.'
      get :home_timeline do
        authenticate!
        current_user.statuses.limit(20)
      end
    end
  end
end

First, you'll need to make the following changes:

• derive from Grape::API::Instance rather than Grape::API
• change the helpers call to replace the block parameter with a named module

You'll also need to use T.bind(self, T.all(Grape::Endpoint, <HelpersModuleName>)) in helper methods that use methods provided by Grape (e.g. env in current_user or error! in authenticate!) or other methods from the same helper module (e.g. current_user in authenticate!).

With the changes:

module Twitter
  class API < Grape::API::Instance
    version 'v1', using: :header, vendor: 'twitter'
    format :json
    prefix :api

    module Helpers
      def current_user
        T.bind(self, T.all(Grape::Endpoint, Helpers))
        @current_user ||= User.authorize!(env)
      end

      def authenticate!
        T.bind(self, T.all(Grape::Endpoint, Helpers))
        error!('401 Unauthorized', 401) unless current_user
      end
    end
    helpers Helpers

    resource :statuses do
      desc 'Return a personal timeline.'
      get :home_timeline do
        authenticate!
        current_user.statuses.limit(20)
      end
    end
  end
end

At this point Sorbet is still reporting errors in the get :home_timeline block, because it doesn't know that these blocks are executed in a context where the Helpers module methods will be available. The Tapioca compiler provided by this gem will fix that. Run bundle exec tapioca dsl. This should generate a sorbet/rbi/dsl/twitter/api.rbi file (assuming the source file is in lib/twitter/api.rb).

After this, Sorbet should no longer report any errors.

Grape overrides Grape::API.new and uses the inherited hook so that subclasses of Grape::API are really subclasses of Grape::API::Instance.

This might be fixable in a future update of grape_sorbet, but is very low priority.

Possibly fixable in a future update.

Possibly fixable in a future update.

The compiler already generates proper signatures for callback methods so T.bind should not be needed (and is in fact unneeded for the other callback methods, before_validation, after_validation and finally). The reason it doesn't work for before and after is because of a bug in Sorbet itself.

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 the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/thatch-health/grape_sorbet. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

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

Everyone interacting in the TestGem project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.