Re-generate Shrine.rb attached file versions for a Rails model

shrine_attachment_version_regenerate.rb

# Run in smalls batches, for memory usage and to re-start on failure / SSH connexion lost

600.times { |i|
  n = i * 100
  puts "Processing #{n} ..."
  Imaj.where(id: (n + 1)..(n + 100)).each { |e|
    e.update!(picture: e.picture[:original]) if e.picture_attacher.stored?
  }
}