Hyperclient

Hyperclient is a Hypermedia API client written in Ruby. It fully supports JSON HAL.

Usage

The examples in this README use the Splines Demo API running here. If you're upgrading from a previous version, please make sure to read UPGRADING.

API Client

Create an API client.

require 'hyperclient'

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api')

By default, Hyperclient adds application/hal+json as Content-Type and Accept headers. It will also send requests as JSON and parse JSON responses. Specify additional headers or authentication if necessary.

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api') do |client|
  client.headers['Access-Token'] = 'token'
end

Hyperclient constructs a connection using typical Faraday middleware for handling JSON requests and responses. You can specify additional Faraday middleware if necessary.

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api') do |client|
  client.connection do |conn|
    conn.use Faraday::Request::OAuth
  end
end

You can pass options to the Faraday connection block in the connection block:

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api') do |client|
  client.connection(ssl: { verify: false }) do |conn|
    conn.use Faraday::Request::OAuth
  end
end

Or when using the default connection configuration you can use faraday_options:

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api') do |client|
  client.faraday_options = { ssl: { verify: false } }
end

You can build a new Faraday connection block without inheriting default middleware by specifying default: false in the connection block.

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api') do |client|
  client.connection(default: false) do |conn|
    conn.request :json
    conn.response :json, content_type: /\bjson$/
    conn.adapter :net_http
  end
end

You can modify headers or specify authentication after a connection has been created. Hyperclient supports Basic, Token or Digest auth as well as many other Faraday extensions.

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api')
api.digest_auth('username', 'password')
api.headers.update('Accept-Encoding' => 'deflate, gzip')

You can access the Faraday connection directly after it has been created and add middleware to it. As an example, you could use the faraday-http-cache-middleware.

api = Hyperclient.new('https://grape-with-roar.herokuapp.com/api')
api.connection.use :http_cache

Resources and Attributes

Hyperclient will fetch and discover the resources from your API.

api.splines.each do |spline|
  puts "A spline with ID #{spline.uuid}."
end

Links and Embedded Resources

The splines example above followed a link called "splines". While you can, you do not need to specify the HAL navigational structure, including links or embedded resources. Hyperclient will resolve these for you. If you prefer, you can explicitly navigate the link structure via _links. In the following example the "splines" link leads to a collection of embedded splines. Invoking api.splines is equivalent to api._links.splines._embedded.splines.

api._links.splines

Templated Links

Templated links require variables to be expanded. For example, the demo API has a link called "spline" that requires a spline "uuid".

spline = api.spline(uuid: 'uuid')
puts "Spline #{spline.uuid} is #{spline.reticulated ? 'reticulated' : 'not reticulated'}."

Invoking api.spline(uuid: 'uuid').reticulated is equivalent to api._links.spline._expand(uuid: 'uuid')._resource._attributes.reticulated.

The client is responsible for supplying all the necessary parameters. Templated links don't do any strict parameter name checking and don't support required vs. optional parameters. Parameters not declared by the API will be dropped and will not have any effect when passed to _expand.

Curies

Curies are named tokens that you can define in the document and use to express curie relation URIs in a friendlier, more compact fashion. For example, the demo API contains very long links to images that use an "images" curie. Hyperclient handles curies and resolves these into full links automatically.

puts spline['image:thumbnail'] # => https://grape-with-roar.herokuapp.com/api/splines/uuid/images/thumbnail.jpg

Attributes

Resource attributes can also be accessed as a hash.

puts spline.to_h # => {"uuid" => "uuid", "reticulated" => true}

The above is equivalent to spline._attributes.to_h.

HTTP

Hyperclient uses Faraday under the hood to perform HTTP calls. You can call any valid HTTP method on any resource.

For example, you can examine the API raw JSON by invoking _get and examining the _response.body hash.

api._get
api._response.body

Other methods, including _head or _options are also available.

spline = api.spline(uuid: 'uuid')
spline._head
spline._options

Invoke _post to create resources.

splines = api.splines
splines._post(uuid: 'new uuid', reticulated: false)

Invoke _put or _patch to update resources.

spline = api.spline(uuid: 'uuid')
spline._put(reticulated: true)
spline._patch(reticulated: true)

Invoke _delete to destroy a resource.

spline = api.spline(uuid: 'uuid')
spline._delete

HTTP methods always return a new instance of Resource.

Testing Using Hyperclient

You can combine RSpec, Faraday::Adapter::Rack and Hyperclient to test your HAL API without having to ever examine the raw JSON response.

describe Acme::Api do
  def app
    Acme::App.instance
  end

  let(:client) do
    Hyperclient.new('http://example.org/api') do |client|
      client.connection(default: false) do |conn|
        conn.request :json
        conn.response :json
        conn.use Faraday::Adapter::Rack, app
      end
    end
  end

  it 'splines returns 3 splines by default' do
    expect(client.splines.count).to eq 3
  end
end

For a complete example refer to this Splines Demo API test.

Reference

Hyperclient API Reference.

Contributing

Hyperclient is work of many people. You're encouraged to submit pull requests, propose features and discuss issues. See CONTRIBUTING for details.

flanker/hyperclient