Custom URL storage for Shrine
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Rakefile Initial commit Jul 11, 2016
shrine-url.gemspec

README.md

Shrine::Storage::Url

Provides a "storage" for Shrine for attaching uploaded files defined by a custom URL.

Installation

gem "shrine-url", "~> 2.0"

Usage

require "shrine/storage/url"

Shrine.storages[:cache] = Shrine::Storage::Url.new

The custom URL should be assigned to the id field in the Shrine uploaded file JSON representation:

{
  "id": "http://example.com/image.jpg",
  "storage": "cache",
  "metadata": {
    # ...
  }
}

Now you can assign this data as the cached attachment:

photo = Photo.new(image: data)
photo.image #=> #<Shrine::UploadedFile>
photo.image.url           #=> "http://example.com/image.jpg"

No HTTP requests are made when file is assigned (but you can load the restore_cached_data Shrine plugin if you want metadata to be extracted on assignment). When this "cached file" is about to be uploaded to a permanent storage, shrine-url will download the file from the given URL using Down.

uploaded_file.download      # Sends a GET request and streams body to Tempfile
uploaded_file.open { |io| } # Sends a GET request and yields `Down::ChunkedIO` ready for reading
uploaded_file.exists?       # Sends a HEAD request and returns true if response status is 2xx
uploaded_file.delete        # Sends a DELETE request

By default the Down::Http backend will be used for downloading, which is implemented using HTTP.rb. You can change the Down backend via the :downloader option:

Shrine::Storage::Url.new(downloader: :wget)
# or
require "down/http"
Shrine::Storage::Url.new(downloader: Down::Http)
# or
require "down/net_http"
Shrine::Storage::Url.new(downloader: Down::NetHttp.new("User-Agent" => "MyApp/1.0.0"))

Note that if you're using permanent storage that supports uploading from a remote URL (like shrine-cloudinary or shrine-uploadcare), downloading will be completely skipped as the permanent storage will use only the URL for uploading the file.

Advantages and Use Cases

The main advantage of using shrine-url over the remote_url Shrine plugin is that you can put downloading from the URL into a background job by loading the backgrounding Shrine plugin. Another advantage is that you can assign multiple remote URLs as multiple versions.

This storage can be used with shrine-transloadit for direct uploads, where a temporary URL of the uploaded file is returned, and we want to use that URL for further background processing, eventually replacing the attachment with processed files.

It is also used in shrine-tus-demo, where the files are uploaded to a separate endpoint, and then its file URL is attached to a database record and promoted to permanent storage.

Contributing

$ rake test

The test suite pulls and runs kennethreitz/httpbin as a Docker container, so you'll need to have Docker installed and running.

License

MIT