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Fantastic file uploading for your web application.


This is the official Ruby gem for Transloadit. It allows you to automate uploading files through the Transloadit REST API.

If you run Ruby on Rails and are looking to integrate with the browser for file uploads, checkout the rails-sdk.


gem install transloadit

Getting started

To get started, you need to require the 'transloadit' gem:

$ irb -rubygems
>> require 'transloadit'
=> true

Then create a Transloadit instance, which will maintain your authentication credentials and allow us to make requests to the API.

transloadit =
  :key    => 'transloadit-auth-key',
  :secret => 'transloadit-auth-secret'

1. Resize and store an image

This example demonstrates how you can create an assembly to resize an image and store the result on Amazon S3.

First, we create two steps: one to resize the image to 320x240, and another to store the image in our S3 bucket.

resize = transloadit.step 'resize', '/image/resize',
  :width  => 320,
  :height => 240

store  = transloadit.step 'store', '/s3/store',
  :key    => 'aws-access-key-id',
  :secret => 'aws-secret-access-key',
  :bucket => 's3-bucket-name'

Now that we have the steps, we create an assembly (which is just a request to process a file or set of files) and let Transloadit do the rest.

assembly = transloadit.assembly(
  :steps => [ resize, store ]

response = assembly.submit! open('lolcat.jpg')

# loop until processing is finished
until response.finished?
  sleep 1; response.reload! # you'll want to implement a timeout in your production app

if response.error?
 # handle error
 # handle other cases

When the submit! method returns, the file has been uploaded but may not yet be done processing. We can use the returned object to check if processing has completed, or examine other attributes of the request.

# returns the unique API ID of the assembly
response[:assembly_id] # => '9bd733a...'

# returns the API URL endpoint for the assembly
response[:assembly_url] # => ''

# checks how many bytes were expected / received by transloadit
response[:bytes_expected] # => 92933
response[:bytes_received] # => 92933

# checks if all processing has been finished
response.finished? # => false

# cancels further processing on the assembly
response.cancel! # => true

# checks if processing was succesfully completed
response.completed? # => true

# checks if the processing returned with an error
response.error? # => false

It's important to note that none of these queries are "live" (with the exception of the cancel! method). They all check the response given by the API at the time the assembly was created. You have to explicitly ask the assembly to reload its results from the API.

# reloads the response's contents from the REST API

In general, you use hash accessor syntax to query any direct attribute from the response. Methods suffixed by a question mark provide a more readable way of quering state (e.g., assembly.completed? vs. checking the result of assembly[:ok]). Methods suffixed by a bang make a live query against the Transloadit HTTP API.

2. Uploading multiple files

Multiple files can be given to the submit! method in order to upload more than one file in the same request. You can also pass a single step for the steps parameter, without having to wrap it in an Array.

assembly = transloadit.assembly(steps: store)

response = assembly.submit!(

You can also pass an array of files to the submit! method. Just unpack the array using the splat * operator.

files = [open('puppies.jpg'), open('kittens.jpg'), open('ferrets.jpg')]
response = assembly.submit! *files

3. Parallel Assembly

Transloadit allows you to perform several processing steps in parallel. You simply need to use other steps. Following their example:

encode = transloadit.step 'encode', '/video/encode', { ... }
thumbs = transloadit.step 'thumbs', '/video/thumbs', { ... }
export = transloadit.step 'store',  '/s3/store',     { ... }

export.use [ encode, thumbs ]

  :steps => [ encode, thumbs, export ]
).submit! open('ninja-cat.mpg')

You can also tell a step to use the original uploaded file by passing the Symbol :original instead of another step.

Check the YARD documentation for more information on using use.

4. Using a Template

Transloadit allows you to use custom templates for recurring encoding tasks. In order to use these do the following:

  :template_id => 'YOUR_TEMPLATE_ID'
).submit! open('ninja-cat.mpg')

You can use your steps together with this template and even use variables. The Transloadit documentation has some nice examples for that.

5. Using fields

Transloadit allows you to submit form field values that you'll get back in the notification. This is quite handy if you want to add additional custom meta data to the upload itself. You can use fields like the following:

  :fields => {:tag => 'ninjacats'}
).submit! open('ninja-cat.mpg')

6. Notify URL

If you want to be notified when the processing is finished you can provide a notify url for the assembly.

  :notify_url => ''
).submit! open('ninja-cat.mpg')

Read up more on the notifications on Transloadit's documentation page


Up-to-date YARD documentation is automatically generated. You can view the docs for the released gem or for the latest git master.


At a minimum, this gem should work on MRI 2.3.0, 2.2.0, 2.1.0, Rubinius, and JRuby. It may also work on older ruby versions, but support for those Rubies is not guaranteed. If it doesn't work on one of the officially supported Rubies, please file a bug report. Compatibility patches for other Rubies are welcome.

Testing against these versions is performed automatically by Travis CI.

Ruby 1.9.x & 2.0

If you still need support for older versions of Ruby, 1.2.0 is the last version that supports those.