二进制文件电子邮件附件问题

Question

使用Python 3.1.2我有一个问题发送二进制附件文件（JPEG，PDF等） - MIMEText附件工作正常。有问题的代码如下...

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()) 

然而，在调用堆栈一路下滑（见下文回溯），它看起来好像msg.as_string（）已收到其产生的有效载荷附件'字节'类型而不是字符串。

有没有人有任何想法可能会导致这个问题？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

好了 - 太多的无奈和网络搜索之后，我发现这个问题是一个已知的bug适用于Python的3.x中，encoders.py，功能encode_base64，这应改为...

def encode_base64(msg): 
    """Encode the message's payload in Base64. 

    Also, add an appropriate Content-Transfer-Encoding header. 
    """ 
    orig = msg.get_payload() 
    encdata = _bencode(orig) 

    # new line inserted to ensure all bytes characters are converted to ASCII 
    encdata = str(encdata, "ASCII") 

    msg.set_payload(encdata) 
    msg['Content-Transfer-Encoding'] = 'base64' 

的错误已被提出的问题＃4768，并升级到临界状态 上2010-05-10。希望这将是固定在下一版本（3.1.3？）

问候，艾伦

Answer 2

for file in self.attachments: 
    fp = open(file,"rb")  
    part = MIMEApplication(fp.read())  
    fp.close()  
    encoders.encode_base64(part) 

    # the miracle 
    part.set_payload(part.get_payload().decode('ASCII')) 

    part.add_header('Content-Disposition', 'attachment; filename="%s"' % file)  
    msg.attach(part) 

Answer 3

从this SO answer

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())