compose

# File activestorage/app/models/active_storage/blob.rb, line 150
    def compose(blobs, filename,, content_type: nil, metadata: nil)
      raise ActiveRecord::RecordNotSaved, "All blobs must be persisted." if blobs.any?(&:new_record?)

      content_type ||= blobs.pluck(:content_type).compact.first

      new(filename: filename, content_type: content_type, metadata: metadata, byte_size: blobs.sum(&:byte_size)).tap do |combined_blob|
        combined_blob.compose(blobs.pluck(:key))
        combined_blob.save!
      end
    end