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Direct Upload to Amazon S3 With CORS
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Easily generate a form that allows you to upload directly to Amazon S3. Multi file uploading supported by jquery-fileupload.

Code extracted from Ryan Bates' gallery-jquery-fileupload.


Add this line to your application's Gemfile:

gem 's3_direct_upload'

Then add a new initalizer with your AWS credentials:


S3DirectUpload.config do |c|
  c.access_key_id = ""       # your access key id
  c.secret_access_key = ""   # your secret access key
  c.bucket = ""              # your bucket name

Make sure your AWS S3 CORS settings for your bucket look something like this:


In production the AllowedOrigin key should be your domain.

Add the following js and css to your asset pipeline:


//= require s3_direct_upload


//= require s3_direct_upload_progress_bars


Create a new view that uses the form helper s3_uploader_form:

<%= s3_uploader_form post: model_url, as: "model[image_url]" do %>
  <%= file_field_tag :file, multiple: true %>
<% end %>

Also place this template in the same view for the progress bars:

<script id="template-upload" type="text/x-tmpl">
<div class="upload">
  <div class="progress"><div class="bar" style="width: 0%"></div></div>

Options for form helper

post: -> url in which is POST'd to after file is uploaded to S3. Example: model_url

as: -> parameter value for the POST in which the key will be the URL of the file on S3. If for example this is set to "model[image_url]" then the data posted would be model[image_url] :

Persisting the S3 url

It is recommended that you persist the image_url that is sent back from the POST request (to the url given to the post option and as the key given as the as option). So to access your files later.

One way to do this is to make sure you have resources model in your routes file, and add the image_url (or whatever you would like to name it) attribute to your model, and then make sure you have the create action in your controller for that model.

You could then have your create action render a javascript file like this: create.js.erb

<% if @model.new_record? %>
  alert("Failed to upload model: <%= j @model.errors.full_messages.join(', ').html_safe %>");
<% else %>
  $("#container").append("<%= j render(@model) %>");
<% end %>

So that javascript code would be executed after the model instance is created, without a page refresh. See @rbates's gallery-jquery-fileupload) for an example of that method.

Advanced Customizations

Feel free to override the styling for the progress bars in s3_direct_upload_progress_bars.css, look at the source for inspiration.

Also feel free to write your own js to interface with jquery-file-upload. You might want to do this to do custom validations on the files before it is sent to S3 for example. To do this remove s3_direct_upload from your application.js and include the necissary jquery-file-upload scripts in your asset pipeline (they are included in this gem automatically):

//= require jquery-fileupload/basic
//= require jquery-fileupload/vendor/tmpl

Use the javascript in s3_direct_upload as a guide.


Right now you can only have one upload form on a page.

Upload form is hardcoded with id '#fileupload'

Contributing / TODO

This is just a simple gem that only really provides some javascript and a form helper. This gem could go all sorts of ways based on what people want and how people contribute. Ideas:

  • More specs!
  • More options to control files expiration, max filesize, file types etc.
  • More convention over configuration on rails side
  • Create generators.
  • Model methods.


This gem is basically a small wrapper around code that Ryan Bates wrote for Railscast#383. Most of the code in this gem was extracted from gallery-jquery-fileupload.

Thank you Ryan Bates!

This code also uses the excellecnt jQuery-File-Upload, which is included in this gem by its rails counterpart jquery-fileupload-rails

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