class ActiveStorage::Attached::Many

document.images.attach([ first_blob, second_blob ])
document.images.attach(io: File.open("/path/to/racecar.jpg"), filename: "racecar.jpg", content_type: "image/jpg")
document.images.attach(params[:signed_blob_id]) # Signed reference to blob from direct upload
document.images.attach(params[:images]) # Array of ActionDispatch::Http::UploadedFile objects

Associates one or several attachments with the current record, saving them to the database.

def attach(*attachables)
  attachables.flatten.collect do |attachable|
    if record.new_record?
      attachments.build(record: record, blob: create_blob_from(attachable))
    else
      attachments.create!(record: record, blob: create_blob_from(attachable))
    end
  end
end