Spyke

Interact with remote REST services in an ActiveRecord-like manner.

Spyke basically ~~rips off~~ takes inspiration 😇 from Her, a gem which we sadly had to abandon as it gave us some performance problems and maintenance seemed to have gone stale.

We therefore made Spyke which adds a few fixes/features needed for our projects:

Fast handling of even large amounts of JSON
Proper support for scopes
Ability to define custom URIs for associations
ActiveRecord-like log output
Handling of API-side validations
Googlable name! :)

Configuration

Add this line to your application's Gemfile:

gem 'spyke'

Spyke uses Faraday to handle requests and expects it to parse the response body into a hash in the following format:

{ data: { id: 1, name: 'Bob' }, metadata: {}, errors: {} }

So, for example for an API that returns JSON like this:

{ "result": { "id": 1, "name": "Bob" }, "extra": {}, "errors": {} }

...the simplest possible configuration that could work is something like this:

# config/initializers/spyke.rb

class JSONParser < Faraday::Response::Middleware
  def parse(body)
    json = MultiJson.load(body, symbolize_keys: true)
    {
      data: json[:result],
      metadata: json[:extra],
      errors: json[:errors]
    }
  rescue MultiJson::ParseError => exception
    { errors: { base: [ error: exception.message ] } }
  end
end

Spyke::Config.connection = Faraday.new(url: 'http://api.com') do |c|
  c.request   :json
  c.use       JSONParser
  c.adapter   Faraday.default_adapter
end

Usage

Adding a class and inheriting from Spyke::Base will allow you to interact with the remote service:

class User < Spyke::Base
  has_many :posts

  scope :active, -> { where(active: true) }
end

User.all
# => GET http://api.com/users

User.active
# => GET http://api.com/users?active=true

User.where(age: 3).active
# => GET http://api.com/users?active=true&age=3

user = User.find(3)
# => GET http://api.com/users/3

user.posts
# => find embedded in returned JSON or GET http://api.com/users/3/posts

user.update_attributes(name: 'Alice')
# => PUT http://api.com/users/3 - { user: { name: 'Alice' } }

user.destroy
# => DELETE http://api.com/users/3

User.create(name: 'Bob')
# => POST http://api.com/users - { user: { name: 'Bob' } }

Custom URIs

You can specify custom URIs on both the class and association level:

class User < Spyke::Base
  uri '/v1/users/(:id)' # id optional, both /v1/users and /v1/users/4 are valid

  has_many :posts, uri: '/posts/for_user/:user_id' # user_id is required
  has_one :image, uri: nil # only use embedded JSON
end

class Post < Spyke::Base
end

user = User.find(3) # => GET http://api.com/v1/users/3
user.image # Will only use embedded JSON and never call out to api
user.posts # => GET http://api.com/posts/for_user/3
Post.find(4) # => GET http://api.com/posts/4

Log output

When used with Rails, Spyke will automatically output helpful ActiveRecord-like messages to the main log:

Started GET "/posts" for 127.0.0.1 at 2014-12-01 14:31:20 +0000
Processing by PostsController#index as HTML
  Parameters: {}
  Spyke (40.3ms)  GET http://api.com/posts [200]
Completed 200 OK in 75ms (Views: 64.6ms | Spyke: 40.3ms | ActiveRecord: 0ms)

API-side validations

Spyke expects errors to be formatted in the same way as the ActiveModel::Errors hash, ie:

{ title: [{ error: 'blank'}, { error: 'too_short', count: 10 }]}

If the API you're using returns errors in a different format you can remap it in Faraday to match the above. Doing this will allow you to show errors returned from the server in forms and f.ex using @post.errors.full_messages just like ActiveRecord.

Contributing

If possible please take a look at the tests marked "wishlisted"! These are features/fixes we want to implement but haven't gotten around to doing yet :)