For using dropzone with rails

dropzone_config.coffee

Dropzone.autoDiscover = false
new_photo_dropzone = new Dropzone('div#new_photo_dropzone', url: '/file/post')
Dropzone.options.new_photo_dropzone =
  paramName: 'file'
  maxFilesize: 2
Dropzone.options.myAwesomeDropzone =
  init: ->
    @on 'processing', (file) ->
      @options.url = '/some-other-url'
  uploadMultiple: false
  paramName: 'file'
  thumbnailWidth: 400
  thumbnailHeight: 400
  thumbnailMethod: 'contain'
  resizeWidth: 640
  resizeMimeType: 'image/jpeg'
  resizeQuality: 0.9
  resizeMethod: 'contain'
  maxFiles: 1
  maxFilesize: 10
  acceptedFiles: 'image/*'
  autoProcessQueue: false
  addRemoveLinks: true
  previewsContainer: 'dropzone-container'

form.haml

 .clsbox-1{runat: "server"}
   #new_photo_dropzone.dropzone.clsbox
   .dropzone-container
      .dropzone-previews