Rails download of AWS S3 file using presigned_post - fatal exception

问题

I set up my Rails app to upload files directly to AWS S3 using this tutorial and it works great. Now I'm working on the direct download piece using the same approach in this SO post. When I try and trigger the download it hangs and then finally returns the following error:

fatal at /user/doc_uploads/download exception reentered

The puts in the code below show what appears to be an infinite loop on the server. I simply don't know enough about how this code is supposed to work to figure this out. Please help!

doc_uploads_controller.rb

def get
    @doc_download = @user.doc_uploads.find_by_id(params[:id])
    if @doc_download
      key = @doc_download.file_url.split('amazonaws.com/')[1]
      puts key
      puts S3_BUCKET_NAME
      bucketlink = S3_BUCKET_NAME.object(key).presigned_url(‌​:get, expires_in: 3600)
      puts bucketlink
      redirect_to bucketlink
    else
      flash[:error]="Something went wrong."
      redirect_to user_dashboard_path
    end
  end

aws.rb:

Aws.config.update({
  region: 'us-east-1',
  credentials: Aws::Credentials.new(ENV['AWS_ACCESS_KEY_ID'], ENV['AWS_SECRET_ACCESS_KEY']),
})

S3_BUCKET_NAME = Aws::S3::Resource.new.bucket(ENV['S3_BUCKET_NAME'])

routes.rb:

get 'user/doc_uploads/download', to: 'doc_uploads#get'

view:

<% @doc_uploads.each do |doc_upload| %>
...
      <%= link_to user_doc_uploads_download_path(id: doc_upload.id), target: '_blank' do %>
        <p class="glyphicon glyphicon-download-alt"></p>
      <% end %>
...
<% end %>

Thanks in advance!

回答1:

If you are able to get url properly in your code, So you can also able to read image from that url.

Try this:

def get
  @doc_download = @user.doc_uploads.find_by_id(params[:id])
  if @doc_download
    data = open(@doc_download.file_url) 
    send_data data.read, filename: 'filename', stream: 'true', buffer_size: '4096'
  else
    flash[:error]="Something went wrong."
    redirect_to user_dashboard_path
  end
end

回答2:

Found a recent post here and got their solution working, as:

presigner = Aws::S3::Presigner.new
url = presigner.presigned_url(:get_object, bucket: ENV['S3_BUCKET_NAME'], key: key, expires_in: 3600, response_content_disposition: "attachment").to_s
redirect_to url

来源：https://stackoverflow.com/questions/42687386/rails-download-of-aws-s3-file-using-presigned-post-fatal-exception