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:mod:`email.utils`: Miscellaneous utilities
-------------------------------------------
.. module:: email.utils
:synopsis: Miscellaneous email package utilities.
**Source code:** :source:`Lib/email/utils.py`
--------------
There are several useful utilities provided in the :mod:`email.utils` module:
.. function:: quote(str)
Return a new string with backslashes in *str* replaced by two backslashes, and
double quotes replaced by backslash-double quote.
.. function:: unquote(str)
Return a new string which is an *unquoted* version of *str*. If *str* ends and
begins with double quotes, they are stripped off. Likewise if *str* ends and
begins with angle brackets, they are stripped off.
.. function:: parseaddr(address)
Parse address -- which should be the value of some address-containing field such
as :mailheader:`To` or :mailheader:`Cc` -- into its constituent *realname* and
*email address* parts. Returns a tuple of that information, unless the parse
fails, in which case a 2-tuple of ``('', '')`` is returned.
.. function:: formataddr(pair, charset='utf-8')
The inverse of :meth:`parseaddr`, this takes a 2-tuple of the form ``(realname,
email_address)`` and returns the string value suitable for a :mailheader:`To` or
:mailheader:`Cc` header. If the first element of *pair* is false, then the
second element is returned unmodified.
Optional *charset* is the character set that will be used in the :rfc:`2047`
encoding of the ``realname`` if the ``realname`` contains non-ASCII
characters. Can be an instance of :class:`str` or a
:class:`~email.charset.Charset`. Defaults to ``utf-8``.
.. versionchanged:: 3.3
Added the *charset* option.
.. function:: getaddresses(fieldvalues)
This method returns a list of 2-tuples of the form returned by ``parseaddr()``.
*fieldvalues* is a sequence of header field values as might be returned by
:meth:`Message.get_all <email.message.Message.get_all>`. Here's a simple
example that gets all the recipients of a message::
from email.utils import getaddresses
tos = msg.get_all('to', [])
ccs = msg.get_all('cc', [])
resent_tos = msg.get_all('resent-to', [])
resent_ccs = msg.get_all('resent-cc', [])
all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)
.. function:: parsedate(date)
Attempts to parse a date according to the rules in :rfc:`2822`. however, some
mailers don't follow that format as specified, so :func:`parsedate` tries to
guess correctly in such cases. *date* is a string containing an :rfc:`2822`
date, such as ``"Mon, 20 Nov 1995 19:12:08 -0500"``. If it succeeds in parsing
the date, :func:`parsedate` returns a 9-tuple that can be passed directly to
:func:`time.mktime`; otherwise ``None`` will be returned. Note that indexes 6,
7, and 8 of the result tuple are not usable.
.. function:: parsedate_tz(date)
Performs the same function as :func:`parsedate`, but returns either ``None`` or
a 10-tuple; the first 9 elements make up a tuple that can be passed directly to
:func:`time.mktime`, and the tenth is the offset of the date's timezone from UTC
(which is the official term for Greenwich Mean Time) [#]_. If the input string
has no timezone, the last element of the tuple returned is ``None``. Note that
indexes 6, 7, and 8 of the result tuple are not usable.
.. function:: parsedate_to_datetime(date)
The inverse of :func:`format_datetime`. Performs the same function as
:func:`parsedate`, but on success returns a :mod:`~datetime.datetime`. If
the input date has a timezone of ``-0000``, the ``datetime`` will be a naive
``datetime``, and if the date is conforming to the RFCs it will represent a
time in UTC but with no indication of the actual source timezone of the
message the date comes from. If the input date has any other valid timezone
offset, the ``datetime`` will be an aware ``datetime`` with the
corresponding a :class:`~datetime.timezone` :class:`~datetime.tzinfo`.
.. versionadded:: 3.3
.. function:: mktime_tz(tuple)
Turn a 10-tuple as returned by :func:`parsedate_tz` into a UTC
timestamp (seconds since the Epoch). If the timezone item in the
tuple is ``None``, assume local time.
.. function:: formatdate(timeval=None, localtime=False, usegmt=False)
Returns a date string as per :rfc:`2822`, e.g.::
Fri, 09 Nov 2001 01:08:47 -0000
Optional *timeval* if given is a floating point time value as accepted by
:func:`time.gmtime` and :func:`time.localtime`, otherwise the current time is
used.
Optional *localtime* is a flag that when ``True``, interprets *timeval*, and
returns a date relative to the local timezone instead of UTC, properly taking
daylight savings time into account. The default is ``False`` meaning UTC is
used.
Optional *usegmt* is a flag that when ``True``, outputs a date string with the
timezone as an ascii string ``GMT``, rather than a numeric ``-0000``. This is
needed for some protocols (such as HTTP). This only applies when *localtime* is
``False``. The default is ``False``.
.. function:: format_datetime(dt, usegmt=False)
Like ``formatdate``, but the input is a :mod:`datetime` instance. If it is
a naive datetime, it is assumed to be "UTC with no information about the
source timezone", and the conventional ``-0000`` is used for the timezone.
If it is an aware ``datetime``, then the numeric timezone offset is used.
If it is an aware timezone with offset zero, then *usegmt* may be set to
``True``, in which case the string ``GMT`` is used instead of the numeric
timezone offset. This provides a way to generate standards conformant HTTP
date headers.
.. versionadded:: 3.3
.. function:: localtime(dt=None)
Return local time as an aware datetime object. If called without
arguments, return current time. Otherwise *dt* argument should be a
:class:`~datetime.datetime` instance, and it is converted to the local time
zone according to the system time zone database. If *dt* is naive (that
is, ``dt.tzinfo`` is ``None``), it is assumed to be in local time. In this
case, a positive or zero value for *isdst* causes ``localtime`` to presume
initially that summer time (for example, Daylight Saving Time) is or is not
(respectively) in effect for the specified time. A negative value for
*isdst* causes the ``localtime`` to attempt to divine whether summer time
is in effect for the specified time.
.. versionadded:: 3.3
.. function:: make_msgid(idstring=None, domain=None)
Returns a string suitable for an :rfc:`2822`\ -compliant
:mailheader:`Message-ID` header. Optional *idstring* if given, is a string
used to strengthen the uniqueness of the message id. Optional *domain* if
given provides the portion of the msgid after the '@'. The default is the
local hostname. It is not normally necessary to override this default, but
may be useful certain cases, such as a constructing distributed system that
uses a consistent domain name across multiple hosts.
.. versionchanged:: 3.2
Added the *domain* keyword.
.. function:: decode_rfc2231(s)
Decode the string *s* according to :rfc:`2231`.
.. function:: encode_rfc2231(s, charset=None, language=None)
Encode the string *s* according to :rfc:`2231`. Optional *charset* and
*language*, if given is the character set name and language name to use. If
neither is given, *s* is returned as-is. If *charset* is given but *language*
is not, the string is encoded using the empty string for *language*.
.. function:: collapse_rfc2231_value(value, errors='replace', fallback_charset='us-ascii')
When a header parameter is encoded in :rfc:`2231` format,
:meth:`Message.get_param <email.message.Message.get_param>` may return a
3-tuple containing the character set,
language, and value. :func:`collapse_rfc2231_value` turns this into a unicode
string. Optional *errors* is passed to the *errors* argument of :class:`str`'s
:func:`~str.encode` method; it defaults to ``'replace'``. Optional
*fallback_charset* specifies the character set to use if the one in the
:rfc:`2231` header is not known by Python; it defaults to ``'us-ascii'``.
For convenience, if the *value* passed to :func:`collapse_rfc2231_value` is not
a tuple, it should be a string and it is returned unquoted.
.. function:: decode_params(params)
Decode parameters list according to :rfc:`2231`. *params* is a sequence of
2-tuples containing elements of the form ``(content-type, string-value)``.
.. rubric:: Footnotes
.. [#] Note that the sign of the timezone offset is the opposite of the sign of the
``time.timezone`` variable for the same timezone; the latter variable follows
the POSIX standard while this module follows :rfc:`2822`.
|
