Question

I’m using CarrierWave to store files in gridfs, but having problems with opening them from my model.
Here are my configs:

/config/initialize/carrierwave.rb

 CarrierWave.configure do |config|
  config.grid_fs_database = Mongoid.database.name
  config.grid_fs_host = Mongoid.config.master.connection.host
  config.storage = :grid_fs
  config.grid_fs_access_url = "/files"
end

/app/controllers/gridfs_controller.rb

 /require 'mongo' 
        class GridfsController < ActionController::Metal
          def serve
            gridfs_path = env["PATH_INFO"].gsub("/files/", "")
            begin
              gridfs_file = Mongo::GridFileSystem.new(Mongoid.database).open(gridfs_path, 'r')
              self.response_body = gridfs_file.read
              self.content_type = gridfs_file.content_type
            rescue
              self.status = :file_not_found
              self.content_type = 'text/plain'
              self.response_body = ''
            end
          end
        end

/app/uploaders/list_uploader.rb

class ListUploader < CarrierWave::Uploader::Base
  storage :grid_fs
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

and in routes

match "/files/uploads/*path" => "gridfs#serve"

So, I have a model, which have a text file

class Campaign
  include Mongoid::Document
  mount_uploader :list, ListUploader

When I’m calling something like <%=link_to "List", @campaign.list.url %> from my view, it opens fine. But when I’m trying something like File.open("#{campaign.list.url}", "r") from campaign model, it fails. It gives me false even when I’m calling File.exists?("/files/uploads/campaign/list/4eb02c4d6b1c0f02b200000b/list.txt"), which is a proper url for that file. So, the question is how should I call it, to open the file from model? And for some reasons, it is important to open it from model. Any suggestions would help, thank you.

Answer 1

Carrierwave url with mongodb gridfs is not a physical path. Its merely a logical route to download the file from gridfs. Thats why you cannot access it from ruby File.open. Check out the below snippet from rails console trying to open the file from gridfs

File.open(User.first.image.pic.url,'r')
Errno::ENOENT: No such file or directory - /images/uploads/e5a1007d34.jpg

see it throw No such file or directory., So you have to download a file instead opening by

>> require 'open-uri'
>> open('image.jpg', 'wb') do |file|
?> file << open('http://0.0.0.0:3000' + (User.first.image.pic.url)).read
>> p file
>> end
#<File:image.jpg>
=> #<File:image.png (closed)>