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