Posted on 11/6/2023 in ruby, httparty

Upload a file with HTTParty without using a temporary file

When you need to upload a file to HTTP POST endpoint using form encoding and you want to use HTTParty to upload data that you have as a string you have two options:

Write to a temp file and upload that
Write the data directly, bypassing the need for a temp file

While you could write the string to a temp file and upload the result it feels a lot cleaner to write the string contents directly.

This is a little more involved and it goes like this:

ruby

require 'httparty'

module YourApiWrapper
  class Base
    include HTTParty

    base_uri 'https://examples.com:/api/v1'
    headers({
              accept: 'application/json',
              authorization: "Bearer: #{ENV['YOUR_AUTH_TOKEN']}"
            })
  end

  class File < Base
    def self.attach(some_id:, file_name:, file_contents:)
      file_to_upload = StringIO.new file_contents

      def file_to_upload.path=(path)
        @path = path
      end

      def file_to_upload.path
        @path
      end

      file_to_upload.path = file_name

      file_to_upload.rewind

      post(
        '/files',
        multipart: true,
        body: {
          file: file_to_upload,
          some_id: some_id
        }
      )
    end
  end
end

require 'httparty'

module YourApiWrapper
  class Base
    include HTTParty

    base_uri 'https://examples.com:/api/v1'
    headers({
              accept: 'application/json',
              authorization: "Bearer: #{ENV['YOUR_AUTH_TOKEN']}"
            })
  end

  class File < Base
    def self.attach(some_id:, file_name:, file_contents:)
      file_to_upload = StringIO.new file_contents

      def file_to_upload.path=(path)
        @path = path
      end

      def file_to_upload.path
        @path
      end

      file_to_upload.path = file_name

      file_to_upload.rewind

      post(
        '/files',
        multipart: true,
        body: {
          file: file_to_upload,
          some_id: some_id
        }
      )
    end
  end
end

Let's break this down, shall we?

The base class contains the basic config for HTTParty, nothing fancy there.

The crucial part is this:

ruby

file_to_upload = StringIO.new file_contents

file_to_upload = StringIO.new file_contents

It creates a StringIO Object, which behaves just like a File, but is created on the fly from data. Yet HTTParty refuses to use it as it lacks one component, and that is a path, or filename if you will.

Ruby's dynamic nature lets us monkeypatch that right into the existing object. As we want it to be dynamic, we need a setter and a getter:

ruby

def file_to_upload.path=(path)
  @path = path
end

def file_to_upload.path
  @path
end

def file_to_upload.path=(path)
  @path = path
end

def file_to_upload.path
  @path
end

And as this is a file, and we're in the 21st century, we must take care to rewind it before we can use it:

ruby

file_to_upload.path = file_name
file_to_upload.rewind

file_to_upload.path = file_name
file_to_upload.rewind

All done, now HTTParty will upload our file:

ruby

post(
  '/files',
  multipart: true,
  body: {
    file: file_to_upload,
    some_id: some_id
  }
)

post(
  '/files',
  multipart: true,
  body: {
    file: file_to_upload,
    some_id: some_id
  }
)

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Upload a file with HTTParty without using a temporary file

Let's break this down, shall we? ​

Let's break this down, shall we?