python - 二进制文件邮件附件问题

Question

使用 Python 3.1.2 我在发送二进制附件文件(jpeg、pdf 等)时遇到问题 - MIMEText 附件工作正常。问题代码如下……

for file in self.attachments:
   part = MIMEBase('application', "octet-stream")
   part.set_payload(open(file,"rb").read())
   encoders.encode_base64(part)
   part.add_header('Content-Disposition', 'attachment; filename="%s"' % file)
   msg.attach(part)   # msg is an instance of MIMEMultipart()

server = smtplib.SMTP(host, port)
server.login(username, password)
server.sendmail(from_addr, all_recipients, msg.as_string())

但是，在调用堆栈的下方(请参阅下面的回溯)，它看起来好像 msg.as_string() 已收到一个附件，该附件创建了“字节”类型而不是字符串的有效负载。

有谁知道可能导致问题的原因是什么？任何帮助将不胜感激。

艾伦

---

builtins.TypeError: string payload expected: <class 'bytes'>
File "c:\Dev\CommonPY\Scripts\email_send.py", line 147, in send
  server.sendmail(self.from_addr, all_recipients, msg.as_string())
File "c:\Program Files\Python31\Lib\email\message.py", line 136, in as_string
  g.flatten(self, unixfrom=unixfrom)
File "c:\Program Files\Python31\Lib\email\generator.py", line 76, in flatten
  self._write(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 101, in _write
  self._dispatch(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 127, in _dispatch
  meth(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 181, in _handle_multipart
  g.flatten(part, unixfrom=False)
File "c:\Program Files\Python31\Lib\email\generator.py", line 76, in flatten
  self._write(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 101, in _write
  self._dispatch(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 127, in _dispatch
  meth(msg)
File "c:\Program Files\Python31\Lib\email\generator.py", line 155, in _handle_text
  raise TypeError('string payload expected: %s' % type(payload))

Answer 1

来自 this SO answer 的解决方案

from base64 import encodebytes
for file in self.attachments:
    fp = open(file, 'rb')
    part = MIMEBase('application', "octet-stream")
    part.set_payload(encodebytes(fp.read()).decode())
    fp.close()
    part.add_header('Content-Transfer-Encoding', 'base64')
    part.add_header('Content-Disposition', 'attachment; filename="%s"' % file)
    msg.attach(part)   # msg is an instance of MIMEMultipart()

server = smtplib.SMTP(host, port)
server.login(username, password)
server.sendmail(from_addr, all_recipients, msg.as_string())