Salestation

Installation

Add this line to your application's Gemfile:

gem 'salestation'

And then execute:

$ bundle

Usage

Using Salestation with Sinatra

First include Salestation::Web. This will provide a method called process to execute a request and Responses module for return codes.

class Webapp < Sinatra::Base
  include Salestation::Web.new
end

Create Salestation application:

  def app
    @_app ||= Salestation::App.new(env: ENVIRONMENT)
  end

Define a route

post '/hello/:name' do
  process(
    HelloUser.call(app.create_request(
      name: params['name']
    )).map(Responses.to_ok)
  )
end

Define chain

class HelloUser
  def self.call(request)
    request >> upcase >> format
  end

  def self.upcase
    -> (request) do
      input.with_input(name: input.fetch(:name).upcase)
    end
  end

  def self.format
    -> (request) do
      name = request.input.fetch(:name)
      Deterministic::Result::Success(message: "Hello #{name}")
    end
  end
end

Using custom errors in error mapper

Salestation allows and recommends you to define your own custom errors. This is useful when your app has error classes that are not general enough for the salestation library.

  include Salestation::Web.new(errors: {
    CustomError => -> (error) { CustomResponse.new(error) }
  })

Using Extractors

Salestation provides extractors to fetch parameters from the request and pass them to the chain. Available extractors are BodyParamExtractor, QueryParamExtractor, ConstantInput, HeadersExtractor. Multiple extractors can be merged together. If two or more extractors use the same key, the value will be from the last extractor in the merge chain.

coercions can optionally be provided to BodyParamExtractor and QueryParamExtractor. These can be used to transform the values of the extracted parameters.

Define a route

include Salestation::Web.new
include Salestation::Web::Extractors

APP = Salestation::App.new(env: {})

def create_app_request
  -> (input) { App.create_request(input) }
end

post '/hello/:name' do |name|
  coercions = {age: ->(age) { age.to_s }}

  extractor = BodyParamExtractor[:age, coercions: coercions]
    .merge(ConstantInput[name: name])
    .merge(HeadersExtractor[{'authorization' => :auth}])

  response = extractor.call(request)
    .map(create_app_request)
    .map(HelloUser)
    .map(Responses.to_ok)

  process(response)
end

Using a logger

Salestation provides a rack logging middleware which can be used to log structured objects.

class Webapp < Sinatra::Base
  # ...
  use Salestation::Web::RequestLogger, my_logger
end

Using StatsD

Salestation provides a StatsD middleware which can be used record request execution time. A timing call with elapsed seconds is made to the provided StatsD instance with path, method, status tags.

class Webapp < Sinatra::Base
  # ...
  use Salestation::Web::StatsdMiddleware,
    Statsd.new(host, port),
    metric: 'my-metric'
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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]/salestation.

License

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