JSONP breaks presenting Entities

[deckchairhq]

To support JSONP requests I am using Rack::JSONP from the 'rack-jsonp' gem:

class MyRouter < Grape::API
  use Rack::JSONP
  use Rack::ContentType, "application/json"

However, when this is enabled my GrapEntities don't 'present' properly, the following is what I get:

http://0.0.0.0:9000/v1/cameras/10?callback=abcDef

returns:

abcDef(#<MyAPI::Entities::V1::Camera:0x007f9d5e82f610>)

However

http://0.0.0.0:9000/v1/cameras/10

returns:

{
  id: 10,
  title: "Test Camera",
  description: "Testing...",
  active: true,
  ...
  minimum_interval: 15
}

The function below illustrates the core of what i'm doing for that route:

    get '/cameras/:camera_id' do
        camera_id = params[:camera_id]
        camera = Camera.includes(:location, :importer).find( camera_id )
        present camera, with: MyAPI::Entities::V1::Camera
    end

Any ideas? I'll keep digging, i'm presuming the issue is the content-type declaration preventing the entity being printed out as JSON. Though I haven't worked my way through Grape's or Grape Entites internals enough yet to be sure.

Cheers,

Gareth

[dblock]

Start by writing a test in Grape that reproduces this. Shouldn't be hard to fix.

[deckchairhq]

Added further description in Pull: #346

[dblock]

JSONP also needs a formatter:

formatter :jsonp, lambda { |object, env| object.to_json }