Skip to content
This repository


Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP

Easy AJAX file uploading in Rails

branch: master

Remove respond_to :json

Setting the `JackUp.Processor` path to `/assets.json` made it not include the
file in the params. Without the `.json`, it correctly saved the Asset record
with the attached file, but then returned a 406 "content not acceptable" error
since the controller only responds to JSON, and it was processed as HTML.

This way it accepts the HTML request and returns JSON to JackUp.
latest commit 645a20f2c4
Gabe Berke-Williams gabebw authored November 18, 2013
Octocat-spinner-32 lib Use 'X-CSRF-Token' in favor of deprecated 'X-Query-Params' August 06, 2012
Octocat-spinner-32 spec Remove respond_to :json November 18, 2013
Octocat-spinner-32 .gitignore Add initial integration specs August 17, 2012
Octocat-spinner-32 .rspec Add initial integration specs August 17, 2012
Octocat-spinner-32 Gemfile Fixes for new version of Capybara November 18, 2013
Octocat-spinner-32 Gemfile.lock Fixes for new version of Capybara November 18, 2013
Octocat-spinner-32 LICENSE Update copyright through 2013 February 22, 2013
Octocat-spinner-32 Remove attr_accessible, update README November 18, 2013
Octocat-spinner-32 Rakefile Add initial integration specs August 17, 2012
Octocat-spinner-32 jack_up.gemspec Upgrade dummy app to Rails 4 November 18, 2013


Easy AJAX file uploading in Rails.


Modify your Gemfile:

gem 'jack_up'

and run bundle install from your shell.

Modify your application.js manifest:

//= require jquery
//= require underscore
//= require jack_up
//= require_tree .


Rails 4.0+, CoffeeScript, and both jQuery and Underscore.js included in your application.js manifest.


Create a JackUp.Processor, binding to various events emitted.

$ -> # when the document is ready
  # create a new processor with the endpoint to where your assets are uploaded
  jackUp = new JackUp.Processor(path: '/assets')

  # called if upload is an image; returns an image jQuery object with src attribute assigned
  jackUp.on 'upload:imageRenderReady', (e, options) ->
    # assigns a data-attribute with the file guid for later referencing
    # set the border color to red, denoting that the image is still being uploaded
    options.image.attr("data-id", options.file.__guid__).css(border: "5px solid red")

  # upload has been sent to server; server will handle processing
  jackUp.on "upload:sentToServer", (e, options) ->
    # change the border color to yellow to signify successful upload (server is still processing)
    $("img[data-id='#{options.file.__guid__}']").css borderColor: 'yellow'

  # when server responds successfully
  jackUp.on "upload:success", (e, options) ->
    # server has completed processing the image and has returned a response
    $("img[data-id='#{options.file.__guid__}']").css(borderColor: "green")

  # when server returns a non-200 response
  jackUp.on "upload:failure", (e, options) ->
    # alert the file name
    alert("'#{}' upload failed; please retry")
    # remove the image from the dom since the upload failed

Once the processor is set up, wire up drag-and-drop support:


  # if you do not want the browser to redirect to the file when droped anywhere else on the page
  $(document).bind 'drop dragover', (e) ->

If you just want to bind to a standard <input type='file'>:


You can use both at the same time, referencing the same JackUp.Processor, in order to provide both options to your users.

Example Rails Setup

For instant file uploading:

# Gemfile
gem 'rails'
gem 'paperclip'
gem 'rack-raw-upload'

Using the rack-raw-upload gem allows for accessing the file posted to the controller via params[:file]; this makes it incredibly easy to handle file uploads.

# app/models/asset.rb
class Asset < ActiveRecord::Base
  has_attached_file :photo

# app/controllers/assets_controller.rb
class AssetsController < ApplicationController
  def create
    @asset = asset_params[:file])

      render json: @asset
      head :bad_request


  def asset_params

This view code could be placed anywhere for immediate uploading:

  %span{ 'data-placeholder' => 'Drop files here' } Drop files here

%input.standard-attachment{ name: 'standard_attachment', accept: 'image/*', type: :file, multiple: :multiple }

Anything with a data-placeholder attribute will be hidden when an file is successfully dropped.

If attaching assets to a different model, additionally use:

# app/models/post.rb
class Post < ActiveRecord::Base
  has_many :assets, dependent: :destroy

  accepts_nested_attributes_for :assets

# app/controllers/posts_controller.rb
class PostsController < ApplicationController
  def new
    @post =

  def create
    @post =
    respond_with @post


  def post_params
    params.require(:post).permit(:asset_ids, :assets_attributes)

To wire up the posts view:

# app/views/posts/new.html.haml
= form_for @post, html: { multipart: true } do |form|
  = form.text_field :title, { placeholder: 'Title' }

    %span{ 'data-placeholder' => 'Drop files here' } Drop files here

  %input.standard-attachment{ name: 'standard_attachment', accept: "image/*", type: :file, multiple: :multiple }

  = form.submit 'Create Post'
# app/assets/javascripts/
# truncated from above to demonstrate additional code to associate uploads
# with posts
jackUp.on "upload:success", (e, options) ->
  $("img[data-id='#{options.file.__guid__}']").css(borderColor: "green")

  # read the response from the server
  asset = JSON.parse(options.responseText)
  assetId =
  # create a hidden input containing the asset id of the uploaded file
  assetIdsElement = $("<input type='hidden' name='post[asset_ids][]'>").val(assetId)
  # append it to the form so saving the form associates the created post
  # with the uploaded assets


JackUp is copyright 2012-2013 Josh Steiner, Josh Clayton, and thoughtbot, inc., and may be redistributed under the terms specified in the LICENSE file.

Something went wrong with that request. Please try again.