Python decode_header 拆分原始字符串

Question

Using Python 3, I'm trying to parse e-mails from an mbox file.

for message in mailbox.mbox('file'):
    sender = message['From']
    c = decode_header(sender)

The raw e-mail has this unique From: header

From: "=?UTF-8?Q?Mark_from_Site?=" <info@site.com>

Anyway, c is

[(b'"', None), (b'Mark from Site', 'utf-8'), (b'" <info@site.com>', None)]

In this case, the line is unexpectedly split following the quotation marks " in multiple elements.

Handling this may be cumbersome, because there may be an undefined number of elements (not always 3 like above) in the list, according to the number of " , and there may also be other causes for splitting.

When there is no string encoding (that is: when the header is pure ascii ), there is no split and c is "Mark from Site" <info@site.com> .

Is there a way to avoid this splitting also for non- ascii encodings?

Or, otherwise, how to correctly parse this kind of headers?

Answer 1

What about doing the simplest thing, ie. converting all parts to Unicode and then glueing them together:

from = ''.join(t[0].decode(t[1] if t[1] else 'UTF-8') for t in decode_header(sender))

Answer 2

You can have the email.header module handle encoding for you by creating an instance of email.header.Header with your string and the charset it should be encoded in.

from email.header import Header

for message in mailbox.mbox('file'):
    sender = Header(message['From'], "utf-8")
    c = decode_header(sender)

Answer 3

str(email.header.make_header(email.header.decode_header(encoded_string)))

Not too obvious, but this should decode and correctly rebuild the header and convert it to a string. I also found this somewhere here on StackOverflow.

Not sure if it's the most elegant way, but seems to work for me.

See https://docs.python.org/3/library/email.header.html for the documentation of these functions.