New submission from Alexander Kruppa:
I'm trying to use the email.* functions to craft HTTP POST data for file
upload. Trying something like
filedata = open("data", "rb").read()
postdata = MIMEMultipart()
fileattachment = MIMEApplication(filedata, _encoder=email.encoders.encode_noop)
postdata.attach(fileattachment)
fp = BytesIO()
g = BytesGenerator(fp)
g.flatten(postdata, unixfrom=False)
fails with
Traceback (most recent call last):
File "./minetest.py", line 30, in <module>
g.flatten(postdata, unixfrom=False)
File "/usr/lib/python3.2/email/generator.py", line 91, in flatten
self._write(msg)
File "/usr/lib/python3.2/email/generator.py", line 137, in _write
self._dispatch(msg)
File "/usr/lib/python3.2/email/generator.py", line 163, in _dispatch
meth(msg)
File "/usr/lib/python3.2/email/generator.py", line 224, in _handle_multipart
g.flatten(part, unixfrom=False, linesep=self._NL)
File "/usr/lib/python3.2/email/generator.py", line 91, in flatten
self._write(msg)
File "/usr/lib/python3.2/email/generator.py", line 137, in _write
self._dispatch(msg)
File "/usr/lib/python3.2/email/generator.py", line 163, in _dispatch
meth(msg)
File "/usr/lib/python3.2/email/generator.py", line 192, in _handle_text
raise TypeError('string payload expected: %s' % type(payload))
TypeError: string payload expected: <class 'bytes'>
This is because BytesGenerator._handle_text() expects str payload in which byte
values that are non-printable in ASCII have been replaced by surrogates. The
example above creates a bytes payload, however, for which
super(BytesGenerator,self)._handle_text(msg) = Generator._handle_text(msg)
throws the exception.
Note that using any email.encoders other than encode_noop does not really fit
the HTTP POST bill, as those define a Content-Transfer-Encoding which HTTP does
not know.
It would seem better to me to let BytesGenerator accept a bytes payload and
just copy that to the output, rather than making the application encode the
bytes as a string, hopefully in a way that s.encode('ascii', 'surrogateescape')
can invert.
E.g., a workaround class I use now does
class FixedBytesGenerator(BytesGenerator):
def _handle_bytes(self, msg):
payload = msg.get_payload()
if payload is None:
return
if isinstance(payload, bytes):
self._fp.write(payload)
elif isinstance(payload, str):
super(FixedBytesGenerator,self)._handle_text(msg)
else:
# Payload is neither bytes not string - this can't be right
raise TypeError('bytes or str payload expected: %s' % type(payload))
_writeBody = _handle_bytes
----------
components: Library (Lib)
messages: 176476
nosy: Alexander.Kruppa
priority: normal
severity: normal
status: open
title: email.generator.BytesGenerator fails with bytes payload
type: behavior
versions: Python 3.2
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue16564>
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