Class: Shrine::Plugins::KitheChecksumSignatures

Inherits:
Object
  • Object
show all
Defined in:
lib/shrine/plugins/kithe_checksum_signatures.rb

Overview

Using the shrine signature and add_metadata plugins, ensure that the shrine standard digest/checksum signatures are recorded in metadata.

This plugin is NOT included in Kithe::AssetUploader by default, include it in your local uploader if desired.

We want to store md5 and sha1 checksums (legacy compat), as well as sha512 (more recent digital preservation recommendation: ocfl.io/draft/spec/#digests)

We only calculate them only on promotion action (not cache action), to avoid needlessly expensive double-computation, and because for direct uploads/backgrounding, we haven’t actually gotten the file in our hands to compute checksums until then anyway.

the add_metadata plugin’s ‘metadata_method` is used to make md5, sha1, and sha512 methods available on the Attacher. (They also end up delegated from the Asset model)

Class Method Summary collapse

Class Method Details

.configure(uploader, opts = {}) ⇒ Object 



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# File 'lib/shrine/plugins/kithe_checksum_signatures.rb', line 24

def self.configure(uploader, opts = {})
  uploader.class_eval do
    add_metadata do |io, derivative:nil, **context|
      if context[:action] != :cache && derivative.nil?
        {
          md5: calculate_signature(io, :md5),
          sha1: calculate_signature(io, :sha1),
          sha512: calculate_signature(io, :sha512)
        }
      end
    end
    metadata_method :md5, :sha1, :sha512
  end
end

.load_dependencies(uploader) ⇒ Object 



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# File 'lib/shrine/plugins/kithe_checksum_signatures.rb', line 19

def self.load_dependencies(uploader, *)
  uploader.plugin :add_metadata
  uploader.plugin :signature
end