Endpoints expecting `multipart/related`?

Hi,

from reading the docs I could find out that grape basically seems to support multiple multipart content types, including multipart/related.

However, the relevant section of the documentation just reads:

Multipart POSTs and PUTs are supported as well.

The request:

curl --form image_file='@image.jpg;type=image/jpg' http://localhost:9292/upload

The Grape endpoint:

post "upload" do
  # file in params[:image_file]
end

I see how that is working for multipart/form-data and it works beautiful for that Content-Type.
However, at the moment I am not sure if that is the right thing to do for an API that is free of classical HTML forms. That is why I thought about using multipart/related instead, expecting a first part with some metadata and a second part with the actual contents of the file (which is btw. the same thing Google Drive does).

However, it is not yet clear to me how that would be possible using grape. When receiving such a request:

• the params do not contain anything except an id and route_info
• env['api.request.body'] is nil
• env['api.request.input'] is nil

Thus I don't see which options I would have to implement such an endpoint using Grape.

Is this a known/intended limitation?
Am I doing it wrong?

Any help is apprechiated.

Best regards and thanks for taking the time to review this issue! 🐈

Start with the documented multipart POST and PUT behavior, then inspect the endpoint handling described in the issue, including params, env['api.request.body'], and env['api.request.input']. Compare the multipart/form-data example with the reported multipart/related request containing metadata and file parts. Done means establishing whether multipart/related is supported or documenting the intended limitation and available integration path.