Multipart::Post

Adds a streamy multipart form post capability to Net::HTTP. Also supports other methods besides POST.

Features/Problems

Appears to actually work. A good feature to have.
Encapsulates posting of file/binary parts and name/value parameter parts, similar to most browsers' file upload forms.
Provides an UploadIO helper class to prepare IO objects for inclusion in the params hash of the multipart post object.

Installation

bundle add multipart-post

Usage

require 'net/http/post/multipart'

url = URI.parse('http://www.example.com/upload')
File.open("./image.jpg") do |jpg|
  req = Net::HTTP::Post::Multipart.new url.path,
    "file" => UploadIO.new(jpg, "image/jpeg", "image.jpg")
  res = Net::HTTP.start(url.host, url.port) do |http|
    http.request(req)
  end
end

To post multiple files or attachments, simply include multiple parameters with UploadIO values:

require 'net/http/post/multipart'

url = URI.parse('http://www.example.com/upload')
req = Net::HTTP::Post::Multipart.new url.path,
  "file1" => UploadIO.new(File.new("./image.jpg"), "image/jpeg", "image.jpg"),
  "file2" => UploadIO.new(File.new("./image2.jpg"), "image/jpeg", "image2.jpg")
res = Net::HTTP.start(url.host, url.port) do |http|
  http.request(req)
end

To post files with other normal, non-file params such as input values, you need to pass hashes to the Multipart.new method.

In Rails 4 for example:

def model_params
  require_params = params.require(:model).permit(:param_one, :param_two, :param_three, :avatar)
  require_params[:avatar] = model_params[:avatar].present? ? UploadIO.new(model_params[:avatar].tempfile, model_params[:avatar].content_type, model_params[:avatar].original_filename) : nil
  require_params
end

require 'net/http/post/multipart'

url = URI.parse('http://www.example.com/upload')
Net::HTTP.start(url.host, url.port) do |http|
  req = Net::HTTP::Post::Multipart.new(url, model_params)
  key = "authorization_key"
  req.add_field("Authorization", key) #add to Headers
  http.use_ssl = (url.scheme == "https")
  http.request(req)
end

Or in plain ruby:

def params(file)
  params = { "description" => "A nice picture!" }
  params[:datei] = UploadIO.new(file, "image/jpeg", "image.jpg")
  params
end

url = URI.parse('http://www.example.com/upload')
File.open("./image.jpg") do |file|
  req = Net::HTTP::Post::Multipart.new(url.path, params(file))
  res = Net::HTTP.start(url.host, url.port) do |http|
    return http.request(req).body
  end
end

Parts Headers

By default, all individual parts will include the header Content-Disposition as well as Content-Length, Content-Transfer-Encoding and Content-Type for the File Parts.

You may optionally configure the headers Content-Type and Content-ID for both ParamPart and FilePart by passing in a parts header.

For example:

url = URI.parse('http://www.example.com/upload')

params = {
  "file_metadata_01" => { "description" => "A nice picture!" },
  "file_content_01"  => UploadIO.new(file, "image/jpeg", "image.jpg")
}

headers = {
  'parts': {
    'file_metadata_01': {
      'Content-Type' => "application/json"
      }
    }
  }

req = Net::HTTP::Post::Multipart.new(uri, params, headers)

This would configure the file_metadata_01 part to include Content-Type

Content-Disposition: form-data; name="file_metadata_01"
Content-Type: application/json
  {
    "description" => "A nice picture!" 
  }

Custom Parts Headers

For FileParts only.

You can include any number of custom parts headers in addition to Content-Type and Content-ID.

headers = {
  'parts': {
    'file_metadata_01': {
      'Content-Type' => "application/json",
      'My-Custom-Header' => "Yo Yo!"
    }
  }
}

Debugging

You can debug requests and responses (e.g. status codes) for all requests by adding the following code:

http = Net::HTTP.new(uri.host, uri.port)
http.set_debug_output($stdout)

Versioning

This library aims to adhere to Semantic Versioning 2.0.0. Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions.

As a result of this policy, you can (and should) specify a dependency on this gem using the Pessimistic Version Constraint with two digits of precision.

For example:

spec.add_dependency 'multipart-post', '~> 2.1'