Allowing User to Download File from S3 Storage - ruby-on-rails-3

Question

Right now I am using Amazon S3 and Paperclip which is allowing my users to upload an image that is associated with the event they are creating. My ultimate goal is since others can view this event, to be able to click on the image and have it prompt a SAVE TO their computer. As of now, clicking the link will open the image in a browser window. I rather have it ask for them to download instead. All images only saved on S3, not local. Need to hide exposed s3 url as well if possible or camouflage it
Here is my current setup
Index.html
<%= link_to 'Download Creative', event.creative.url, class: "btn btn-info" %>
Event.rb
has_attached_file :creative,
:styles => { :thumb => "150x150", :custcreative => "250x75" },
:path => ":attachment/:id/:style.:extension",
:s3_domain_url => "******.s3.amazonaws.com",
:storage => :s3,
:s3_credentials => Rails.root.join("config/s3.yml"),
:bucket => '*****',
:s3_permissions => :public_read,
:s3_protocol => "http",
:convert_options => { :all => "-auto-orient" },
:encode => 'utf8'
Hoping someone can help me out.

Answer 1

To avoid extra load to your app (saving dyno's time in Heroku), I would rather do something like this: add this method to your model with the attachment:
def download_url(style_name=:original)
creative.s3_bucket.objects[creative.s3_object(style_name).key].url_for(:read,
:secure => true,
     :expires => 24*3600,  # 24 hours
     :response_content_disposition => "attachment; filename='#{creative_file_name}'").to_s
end
And then use it in your views/controllers like this:
<%= link_to 'Download Creative', event.download_url, class: "btn btn-info" %>

Answer 2

To make this work, I've just added a new action in the controller, so in your case it could be:
#routes
resources :events do
member { get :download }
end
#index
<%= link_to 'Download Creative', download_event_path(event), class: "btn btn-info" %>
#events_controller
def download
data = open(event.creative_url)
send_data data.read, :type => data.content_type, :x_sendfile => true
end
EDIT:
the correct solution for download controller action can be found here (I've updated the code above): Force a link to download an MP3 rather than play it?

Answer 3

Now in aws-sdk v2, there is a method :presigned_url defined in Aws::S3::Object, you can use this method to construct the direct download url for a s3 object:
s3 = Aws::S3::Resource.new
# YOUR-OBJECT-KEY should be the relative path of the object like 'uploads/user/logo/123/pic.png'
obj = s3.bucket('YOUR-BUCKET-NAME').object('YOUR-OBJECT-KEY')
url = obj.presigned_url(:get, expires_in: 3600, response_content_disposition: "attachment; filename='FILENAME'")
then in your views, just use:
= link_to 'download', url

Answer 4

event = Event.find(params[:id])
data = open(event.creative.url)
send_data data.read, :type => data.content_type, :x_sendfile => true, :url_based_filename => true
end

Answer 5

You need to set the "Content-Disposition" to "attachment" in your HTTP response header. I'm not a Rails developer - so just Google it and you'll see plenty of examples - but it probably looks something like this:
:content_disposition => "attachment"
or
...
:disposition => "attachment"