email.utils: 其他工具

源代码: Lib/email/utils.py

email.utils 模块提供如下几个工具

email.utils.localtime(dt=None)

以感知型 datetime 对象返回当地时间。 如果调用时参数为空，则返回当前时间。 否则 dt 参数应该是一个 datetime 实例，并根据系统时区数据库转换为当地时区。 如果 dt 是简单型的 (即 dt.tzinfo 是 None )，则假定为当地时间。 在这种情况下，为正值或零的 isdst 会使 localtime 假定夏季时间（例如，夏令时）对指定时间生效或不生效。 负值 isdst 会使 localtime 预测夏季时间对指定时间是否生效。

3.3 新版功能.

email.utils.make_msgid(idstring=None, domain=None)

Returns a string suitable for an RFC 2822-compliant 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.

在 3.2 版更改: 增加了关键字 domain

The remaining functions are part of the legacy (Compat32) email API. There is no need to directly use these with the new API, since the parsing and formatting they provide is done automatically by the header parsing machinery of the new API.

email.utils.quote(str)

Return a new string with backslashes in str replaced by two backslashes, and double quotes replaced by backslash-double quote.

email.utils.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.

email.utils.parseaddr(address)

Parse address -- which should be the value of some address-containing field such as To or 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.

email.utils.formataddr(pair, charset='utf-8')

The inverse of parseaddr(), this takes a 2-tuple of the form (realname, email_address) and returns the string value suitable for a To or 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 str or a Charset. Defaults to utf-8.

在 3.3 版更改: Added the charset option.

email.utils.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 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)
email.utils.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 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, parsedate() returns a 9-tuple that can be passed directly to time.mktime(); otherwise None will be returned. Note that indexes 6, 7, and 8 of the result tuple are not usable.

email.utils.parsedate_tz(date)

Performs the same function as parsedate(), but returns either None or a 10-tuple; the first 9 elements make up a tuple that can be passed directly to time.mktime(), and the tenth is the offset of the date's timezone from UTC (which is the official term for Greenwich Mean Time) 1. If the input string has no timezone, the last element of the tuple returned is 0, which represents UTC. Note that indexes 6, 7, and 8 of the result tuple are not usable.

email.utils.parsedate_to_datetime(date)

The inverse of format_datetime(). Performs the same function as parsedate(), but on success returns a 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 timezone tzinfo.

3.3 新版功能.

email.utils.mktime_tz(tuple)

Turn a 10-tuple as returned by parsedate_tz() into a UTC timestamp (seconds since the Epoch). If the timezone item in the tuple is None, assume local time.

email.utils.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 time.gmtime() and 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.

email.utils.format_datetime(dt, usegmt=False)

Like formatdate, but the input is a 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.

3.3 新版功能.

email.utils.decode_rfc2231(s)

Decode the string s according to RFC 2231.

email.utils.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.

email.utils.collapse_rfc2231_value(value, errors='replace', fallback_charset='us-ascii')

When a header parameter is encoded in RFC 2231 format, Message.get_param may return a 3-tuple containing the character set, language, and value. collapse_rfc2231_value() turns this into a unicode string. Optional errors is passed to the errors argument of str's 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 collapse_rfc2231_value() is not a tuple, it should be a string and it is returned unquoted.

email.utils.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).

备注

1

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.