Wrapping Responses with Grape and Rack

Grape’s after blocks don’t allow you to modify response text or status code. So how can you wrap an API response?

Define a Rack middleware and mount it in the API. Here’s an example of a decorator that wraps any body and resets the status code to 200.

class ApiDecorator
  def initialize(app)
    @app = app
  end
  def call(env)
    status, headers, bodies = @app.call(env)
    bodies = bodies.map do |body|
      { body: body, status: status }
    end
    [200, headers, bodies]
  end
end

class MyApi < Grape::API
  use ApiDecorator
  get :ping do
    { ping: 'pong' }
  end
end

You can see a working sample with API_v4_Decorator mounted in API_v4 in https://github.com/dblock/grape-on-rack.

This works with all kinds of Rack applications, not just Grape.

Daniel Doubrovkine

Wrapping Responses with Grape and Rack rack | grape | ruby | api

Wrapping Responses with Grape and Rack