Faraday Multipart

GitHub Workflow Status Gem License

The Multipart middleware converts a Faraday::Request#body Hash of key/value pairs into a multipart form request, but only under these conditions:

  • The request's Content-Type is "multipart/form-data"
  • Content-Type is unspecified, AND one of the values in the Body responds to #content_type.

Faraday contains a couple helper classes for multipart values:

  • Faraday::Multipart::FilePart wraps binary file data with a Content-Type. The file data can be specified with a String path to a local file, or an IO object.
  • Faraday::Multipart::ParamPart wraps a String value with a Content-Type, and optionally a Content-ID.


Add this line to your application's Gemfile:

gem 'faraday-multipart'

And then execute:

bundle install

Or install it yourself as:

gem install faraday-multipart


First of all, you'll need to add the multipart middleware to your Faraday connection:

require 'faraday/multipart'

conn = Faraday.new(...) do |f|
  f.request :multipart
  # ...

Payload can be a mix of POST data and multipart values.

# regular POST form value
payload = { string: 'value' }

# filename for this value is File.basename(__FILE__)
payload[:file] = Faraday::Multipart::FilePart.new(__FILE__, 'text/x-ruby')

# specify filename because IO object doesn't know it
payload[:file_with_name] = Faraday::Multipart::FilePart.new(

# Sets a custom Content-Disposition:
# nil filename still defaults to File.basename(__FILE__)
payload[:file_with_header] = Faraday::Multipart::FilePart.new(
  'Content-Disposition' => 'form-data; foo=1'

# Upload raw json with content type
payload[:raw_data] = Faraday::Multipart::ParamPart.new(
  { a: 1 }.to_json,

# optionally sets Content-ID too
payload[:raw_with_id] = Faraday::Multipart::ParamPart.new(
  { a: 1 }.to_json,

conn.post('/', payload)


After checking out the repo, run bin/setup to install dependencies.

Then, run bin/test to run the tests.

To install this gem onto your local machine, run rake build.

To release a new version, make a commit with a message such as "Bumped to 0.0.2" and then run rake release. See how it works here.


Bug reports and pull requests are welcome on GitHub.


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