I’m working on a project where we are using the Paperclip plugin for Ruby on Rails for file handling and associations with other models.

I’m working on a CSV import option right now, using this tutorial to help me get a head start on how to break the contents of the file up into rows and columns. I’m not passing the file directly from a form to the controller method, but I’m opening the file that has already been saved after being uploaded via AJAX.

I couldn’t find out how I would get the file itself into an object that I can pass to the parser like so:

@parsed_file=CSV::Reader.parse(params[:dump][:file])

It turns out that you simply need to refer to the Paperclip attachment and then use ‘to_file’ like so:

require 'csv'
@upload = Upload.find(params[:upload_id])
@parsed_file = CSV::Reader.parse(@upload.attachment.to_file)