Datatreeview没有显示结果

Question

代码：

def get_file(url, max_segment_size)
  http_client = HTTPClient.new
  segment = nil

  http_client.get_content(url) do |chunk|
    segment.nil? ? segment = chunk : segment << chunk
    if segment.size >= max_segment_size
      # send part to s3
      send_part(segment)
      segment = nil
    end
  end
  # send last part
  send_part(segment) if segment
end

运行datatreeview后，显示列名，但没有内容。