Nobody knows how to upload a file with Ruby Net::HTTP

As a hobby project, I’m currently working on my gem http_wrapper, and right now I’m implementing file uploads. I’m not a big fan of reinventing wheels, especially when someone has already invented a perfectly round one, so the first thing I did was google possible solutions. And this is where it gets funny: I couldn’t find a single one that showed the right way to upload a file with Net::HTTP. People suggest ready-made wrappers (like Rest Client and httparty), or gems that implement multipart/form-data specifically (for example, multipart-post), or even calling curl through a system call. Horrifying, really.

None of that appealed to me, so I started digging through the guts of Net::HTTP. In the end I unearthed a big secret (judging by the fact that I couldn’t find it anywhere else on the internet), and now I’m sharing it with you: how to properly upload a file with Ruby’s standard library Net::HTTP:

require 'net/http'

# prepare the uri we'll be sending the data to
uri = URI 'http://example.com/upload_form'

# set up a new connection
connection = Net::HTTP.new uri.host, uri.port

# create the POST request object
request = Net::HTTP::Post.new uri

# build the form data
form_data = [
  ['user_avatar', File.read('kartinko.jpg'), {filename: 'picture.jpg'}], # file content given as a "string"
  ['user_photo',  File.open('photo.jpg')], # file content given as a File object
  # any other form fields go right here in the same format:
  ['submit', 'true'],
  ['user_name', 'valera']
]

# attach the data to the request
request.set_form form_data, 'multipart/form-data'

# send the request
response = connection.request request

#...

Profit! :)