如何在使用jquery文件上传将原始文件直接上传到s3后使用carrierwave创建缩略图

Question

I am uploading image via jquery_file_upload (Railscast episode #383) The upload work perfectly and i get the url in the callback function

The problem is: I want to create some thumbnails after uploading directly to s3

for that i assume:

1. The server has to read the image from the s3
2. The server has to create the thumbnails
3. The server has to store the thumbnails directly in s3
4. The server has to get callback and display the thumbnails accordingly.
5. The server has to store a field the the thumbnails created

Now, after the image finish to upload the image controller callback called:

def create
 #get the url from the callbcack
 #e.g: image[image_source] = https://<BUCKET>.s3.amazonaws.com/uploads/myimage.png
 @image = Image.new(params[:image])
 @image.user_id = current_user.id
 @image.save
end

And the model:

class Image < ActiveRecord::Base
  attr_accessible :image_thumb, :user_id, :width ,:album_type_id 
  after_save :enqueue_image

  mount_uploader :image_thumb, ImageUploader

  def enqueue_image
   #checking if i have the original image
   if self.image_source present?
    #what to do here?
    #how can i call the carrierwave function to create the thumbnails?
    #how to send the thumbnails directly to s3 with callback name?
   end

  end
end

Answer 1

Do you necessarily need to create the thumbnails after uploading? If not, I think that you can create a thumbnail (or as many sizes as you want) during the initial upload by using version . Example:

 class ImageUploader < CarrierWave::Uploader::Base
    version :thumb do
     process :resize_to_fill => [50, 50]
    end
 end