def as_string(self, unixfrom=False, maxheaderlen=0):
"""Return the entire formatted message as a (unicode) string.
Optional `unixfrom' when True, means include the Unix From_ envelope
header.
This is a convenience method and may not generate the message exactly
as you intend. For more flexibility, use the flatten() method of a
Generator instance.
"""
from future.backports.email.generator import Generator
fp = StringIO()
g = Generator(fp, mangle_from_=False, maxheaderlen=maxheaderlen)
g.flatten(self, unixfrom=unixfrom)
return fp.getvalue()
def _create_boundary(message):
"""Add boundary parameter to multipart message if they are not present."""
if not message.is_multipart() or message.get_boundary() is not None:
return message
# HACK: Python2 lists do not natively have a `copy` method. Unfortunately,
# due to a bug in the Backport for the email module, the method
# `Message.set_boundary` converts the Message headers into a native list,
# so that other methods that rely on "copying" the Message headers fail.
# `Message.set_boundary` is called from `Generator.handle_multipart` if the
# message does not already have a boundary present. (This method itself is
# called from `Message.as_string`.)
# Hence, to prevent `Message.set_boundary` from being called, add a
# boundary header manually.
from future.backports.email.generator import Generator
# pylint: disable=protected-access
boundary = Generator._make_boundary(message.policy.linesep)
message.set_param('boundary', boundary)
return message