Artemis

Artemis is a GraphQL client that is designed to fit well on Rails.

Convention over Configuration: You'll never have to make trivial decisions or spend time on boring setup. Start making a GraphQL request in literally 30s.
Performant by default: You can't do wrong when it comes to performance. All GraphQL files are pre-loaded only once in production and it'll never affect runtime performance. Comes with options that enable persistent connections and even HTTP/2, the next-gen high-performance protocol.
First-class support for testing: Testing and stubbing GraphQL requests couldn't be simpler. No need to add external dependencies to test well.

Battle-tested at Artsy

Quick start

You could set up Artemis with just a few commands. See it in action:

$ bundle add artemis
$ rails g artemis:install artsy https://metaphysics-production.artsy.net/
$ echo '
query($id: String!) {
  artist(id: $id) {
    name
    birthday
   }
}' > app/operations/artsy/artist.graphql
$ rails c
> Artsy.artist(id: "leonardo-da-vinci").data.artist.name     # => "Leonardo da Vinci"
> Artsy.artist(id: "leonardo-da-vinci").data.artist.birthday # => "1452/04/15"

Getting started

Add this line to your application's Gemfile:

gem 'artemis'

And then execute:

$ bundle

Once you run bundle install on your Rails app, run the install command:

$ rails g artemis:install artsy https://metaphysics-production.artsy.net/

You could also use the --authorization option to assign a token so the installer can download the GraphQL schema:

$ rails g artemis:install github https://api.github.com/graphql --authorization 'token ...'

Generating your first query

Artemis comes with a query generator. For exmaple, you could use the query generator to generate a query stub for artist:

$ rails g artemis:query artist

Then this will generate:

# app/operations/artist.graphql
query($id: String!) {
  artist(id: $id) {
    # Add fields here...
  }
}

Then you could the class method that has the matching name artist:

Artsy.artist(id: "pablo-picasso")
# => makes a GraphQL query that's in app/operations/artist.graphql

You can also specify a file name:

$ rails g artemis:query artist artist_details_on_artwork
# => generates app/operations/artist_details_on_artwork.graphql

Then you can make a query in artist_details_on_artwork.graphql with:

Artsy.artist_details_on_artwork(id: "pablo-picasso")

The convention

Artemis assumes that the files related to GraphQL are organized in a certain way. For example, a service that talks to Artsy's GraphQL API could have the following structure:

├──app/operations
│   ├── artsy
│   │   ├── _artist_fragment.graphql
│   │   ├── artwork.graphql
│   │   ├── artist.graphql
│   │   └── artists.graphql
│   └── artsy.rb
├──config/graphql.yml
├──test/fixtures/graphql
│   └── artsy
│       ├── artwork.yml
│       ├── artist.yml
│       └── artists.yml
└──vendor/graphql/schema/artsy.json

Callbacks

Youcan use the before_execute callback to intercept outgoing requests and the after_execute callback to observe the response. A common operation that's done in the before_execute hook is assigning a token to the header:

class Artsy < Artemis::Client
  before_execute do |document, operation_name, variables, context|
    context[:headers] = {
      Authorization: "token ..."
    }
  end
end

Here the :headers key is a special context type. The hash object assigned to the context[:headers] will be sent as the HTTP headers of the request.

Another common thing when receiving a response is to check if there's any error in the response and throw and error accordingly:

class Artsy < Artemis::Client
  after_execute do |data, errors, extensions|
    raise "GraphQL error: #{errors.to_json}" if errors.present?
  end
end

Configuration

You can configure the GraphQL client using the following options. Those configurations are found in the config/graphql.yml.

Name	Required?	Default	Description
`adapter`	No	`:net_http`	The underlying client library that actually makes an HTTP request. See Adapters for available options.
`pool_size`	No	25	The number of keep-alive connections. The `:net_http` adapter will ignore this option.
`schema_path`	No	See above	The path to the GrapQL schema. Setting an empty value to this will force the client to download the schema upon the first request.
`timeout`	No	10	HTTP timeout set for the adapter in seconds. This will be set to both `read_timeout` and `write_timeout` and there is no way to configure them with a different value as of writing (PRs welcome!)
`url`	Yes	N/A	The URL for the GraphQL endpoint.

Adapters

There are four adapter options available. Choose the adapter that best fits on your use case.

Adapter	Protocol	Keep-alive	Performance	Dependencies
`:curb`	HTTP/1.1, HTTP/2	Yes	Fastest	`curb 0.9.6+` `libcurl 7.64.0+` `nghttp2 1.0.0+`
`:net_http` (default)	HTTP/1.1 only	No	Slow	None
`:net_http_persistent`	HTTP/1.1 only	Yes	Fast	`net-http-persistent 3.0.0+`
`:test`	N/A (See Testing)

Third-party adapters

This is a comminuty-maintained adapter. Want to add yours? Send us a pull request!

Adapter	Description
`::net_http_hmac`	provides a new Adapter for the Artemis GraphQL ruby client to support HMAC Authentication using ApiAuth.

Writing your own adapter

When the built-in adapters do not satisfy your needs, you may want to implement your own adapter. You could do so by following the steps below. Let's implement the ::net_http_hmac adapter as an example.

Define NetHttpHmacAdapter under the Artemis::Adapters namespace and implement the #execute method:

# lib/artemis/adapters/net_http_hmac_adapter.rb
module Artemis::Adapters
  class NetHttpHmacAdapter
    def execute(document:, operation_name: nil, variables: {}, context: {})
      # Makes an HTTP request for GraphQL query.
    end
  end
end

Load the adapter in config/initializers/artemis.rb (or any place that gets loaded before Rails runs initializers):
```
require 'artemis/adapters/net_http_hmac_adapter'
```

Specify the adapter name in config/graphql.yml:

default: &default
  adapter: :net_http_hmac

Rake tasks

Artemis also adds a useful rake graphql:schema:update rake task that downloads the GraphQL schema using the Introspection query.

Task Name	Options	Description
`graphql:schema:update`	`SERVICE`: Service name the schema is downloaded from `AUTHORIZATION`: HTTP `Authorization` header value used to download the schema	Downloads and saves the GraphQL schema

Testing

Given that you have app/operations/artsy/artist.graphql and fixture file for the artist.yml:

# test/fixtures/graphql/artist.yml:
leonardo_da_vinci:
  data:
    artist:
      name: Leonardo da Vinci
      birthday: 1452/04/15

yayoi_kusama:
  data:
    artist:
      name: Yayoi Kusama
      birthday: 1929/03/22

Then you can stub the request with the stub_graphql DSL:

stub_graphql(Artsy, :artist, id: "yayoi-kusama").to_return(:yayoi_kusama)
stub_graphql(Artsy, :artist, id: "leonardo-da-vinci").to_return(:leonardo_da_vinci)

yayoi_kusama = Artsy.artist(id: "yayoi-kusama")
yayoi_kusama.data.artist.name     # => "Yayoi Kusama"
yayoi_kusama.data.artist.birthday # => "1452/04/15"

da_vinci = Artsy.artist(id: "leonardo-da-vinci")
da_vinci.data.artist.name     # => "Leonardo da Vinci"
da_vinci.data.artist.birthday # => "1452/04/15"

You can also use JSON instead of YAML. See example fixtures and test cases.

MiniTest

Setting up the test helper with Artemis is very easy and simple. Just add the following code to the test/test_helper.rb in your app:

# spec/test_helper.rb
require 'artemis/test_helper'

class ActiveSupport::TestCase
  setup do
    graphql_requests.clear
    graphql_responses.clear
  end
end

RSpec

Artemis also comes with a script that wires up helper methods on Rspec. Because it is more common to use the spec/ directory to organize spec files in RSpec, the config.artemis.fixture_path config needs to point to spec/fixtures/graphql. Other than that, it is very straightforward to set it up:

# config/application.rb
config.artemis.fixture_path = 'spec/fixtures/graphql'

# Add this to your spec/rails_helper.rb or spec_helper.rb if you don't have rails_helper.rb
require 'artemis/rspec'

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/yuki24/artemis. 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 Artemis project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

daemonsy/artemis