1:mod:`email.utils`: Miscellaneous utilities 2------------------------------------------- 3 4.. module:: email.utils 5 :synopsis: Miscellaneous email package utilities. 6 7**Source code:** :source:`Lib/email/utils.py` 8 9-------------- 10 11There are a couple of useful utilities provided in the :mod:`email.utils` 12module: 13 14.. function:: localtime(dt=None) 15 16 Return local time as an aware datetime object. If called without 17 arguments, return current time. Otherwise *dt* argument should be a 18 :class:`~datetime.datetime` instance, and it is converted to the local time 19 zone according to the system time zone database. If *dt* is naive (that 20 is, ``dt.tzinfo`` is ``None``), it is assumed to be in local time. In this 21 case, a positive or zero value for *isdst* causes ``localtime`` to presume 22 initially that summer time (for example, Daylight Saving Time) is or is not 23 (respectively) in effect for the specified time. A negative value for 24 *isdst* causes the ``localtime`` to attempt to divine whether summer time 25 is in effect for the specified time. 26 27 .. versionadded:: 3.3 28 29 30.. function:: make_msgid(idstring=None, domain=None) 31 32 Returns a string suitable for an :rfc:`2822`\ -compliant 33 :mailheader:`Message-ID` header. Optional *idstring* if given, is a string 34 used to strengthen the uniqueness of the message id. Optional *domain* if 35 given provides the portion of the msgid after the '@'. The default is the 36 local hostname. It is not normally necessary to override this default, but 37 may be useful certain cases, such as a constructing distributed system that 38 uses a consistent domain name across multiple hosts. 39 40 .. versionchanged:: 3.2 41 Added the *domain* keyword. 42 43 44The remaining functions are part of the legacy (``Compat32``) email API. There 45is no need to directly use these with the new API, since the parsing and 46formatting they provide is done automatically by the header parsing machinery 47of the new API. 48 49 50.. function:: quote(str) 51 52 Return a new string with backslashes in *str* replaced by two backslashes, and 53 double quotes replaced by backslash-double quote. 54 55 56.. function:: unquote(str) 57 58 Return a new string which is an *unquoted* version of *str*. If *str* ends and 59 begins with double quotes, they are stripped off. Likewise if *str* ends and 60 begins with angle brackets, they are stripped off. 61 62 63.. function:: parseaddr(address) 64 65 Parse address -- which should be the value of some address-containing field such 66 as :mailheader:`To` or :mailheader:`Cc` -- into its constituent *realname* and 67 *email address* parts. Returns a tuple of that information, unless the parse 68 fails, in which case a 2-tuple of ``('', '')`` is returned. 69 70 71.. function:: formataddr(pair, charset='utf-8') 72 73 The inverse of :meth:`parseaddr`, this takes a 2-tuple of the form ``(realname, 74 email_address)`` and returns the string value suitable for a :mailheader:`To` or 75 :mailheader:`Cc` header. If the first element of *pair* is false, then the 76 second element is returned unmodified. 77 78 Optional *charset* is the character set that will be used in the :rfc:`2047` 79 encoding of the ``realname`` if the ``realname`` contains non-ASCII 80 characters. Can be an instance of :class:`str` or a 81 :class:`~email.charset.Charset`. Defaults to ``utf-8``. 82 83 .. versionchanged:: 3.3 84 Added the *charset* option. 85 86 87.. function:: getaddresses(fieldvalues) 88 89 This method returns a list of 2-tuples of the form returned by ``parseaddr()``. 90 *fieldvalues* is a sequence of header field values as might be returned by 91 :meth:`Message.get_all <email.message.Message.get_all>`. Here's a simple 92 example that gets all the recipients of a message:: 93 94 from email.utils import getaddresses 95 96 tos = msg.get_all('to', []) 97 ccs = msg.get_all('cc', []) 98 resent_tos = msg.get_all('resent-to', []) 99 resent_ccs = msg.get_all('resent-cc', []) 100 all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs) 101 102 103.. function:: parsedate(date) 104 105 Attempts to parse a date according to the rules in :rfc:`2822`. however, some 106 mailers don't follow that format as specified, so :func:`parsedate` tries to 107 guess correctly in such cases. *date* is a string containing an :rfc:`2822` 108 date, such as ``"Mon, 20 Nov 1995 19:12:08 -0500"``. If it succeeds in parsing 109 the date, :func:`parsedate` returns a 9-tuple that can be passed directly to 110 :func:`time.mktime`; otherwise ``None`` will be returned. Note that indexes 6, 111 7, and 8 of the result tuple are not usable. 112 113 114.. function:: parsedate_tz(date) 115 116 Performs the same function as :func:`parsedate`, but returns either ``None`` or 117 a 10-tuple; the first 9 elements make up a tuple that can be passed directly to 118 :func:`time.mktime`, and the tenth is the offset of the date's timezone from UTC 119 (which is the official term for Greenwich Mean Time) [#]_. If the input string 120 has no timezone, the last element of the tuple returned is ``None``. Note that 121 indexes 6, 7, and 8 of the result tuple are not usable. 122 123 124.. function:: parsedate_to_datetime(date) 125 126 The inverse of :func:`format_datetime`. Performs the same function as 127 :func:`parsedate`, but on success returns a :mod:`~datetime.datetime`. If 128 the input date has a timezone of ``-0000``, the ``datetime`` will be a naive 129 ``datetime``, and if the date is conforming to the RFCs it will represent a 130 time in UTC but with no indication of the actual source timezone of the 131 message the date comes from. If the input date has any other valid timezone 132 offset, the ``datetime`` will be an aware ``datetime`` with the 133 corresponding a :class:`~datetime.timezone` :class:`~datetime.tzinfo`. 134 135 .. versionadded:: 3.3 136 137 138.. function:: mktime_tz(tuple) 139 140 Turn a 10-tuple as returned by :func:`parsedate_tz` into a UTC 141 timestamp (seconds since the Epoch). If the timezone item in the 142 tuple is ``None``, assume local time. 143 144 145.. function:: formatdate(timeval=None, localtime=False, usegmt=False) 146 147 Returns a date string as per :rfc:`2822`, e.g.:: 148 149 Fri, 09 Nov 2001 01:08:47 -0000 150 151 Optional *timeval* if given is a floating point time value as accepted by 152 :func:`time.gmtime` and :func:`time.localtime`, otherwise the current time is 153 used. 154 155 Optional *localtime* is a flag that when ``True``, interprets *timeval*, and 156 returns a date relative to the local timezone instead of UTC, properly taking 157 daylight savings time into account. The default is ``False`` meaning UTC is 158 used. 159 160 Optional *usegmt* is a flag that when ``True``, outputs a date string with the 161 timezone as an ascii string ``GMT``, rather than a numeric ``-0000``. This is 162 needed for some protocols (such as HTTP). This only applies when *localtime* is 163 ``False``. The default is ``False``. 164 165 166.. function:: format_datetime(dt, usegmt=False) 167 168 Like ``formatdate``, but the input is a :mod:`datetime` instance. If it is 169 a naive datetime, it is assumed to be "UTC with no information about the 170 source timezone", and the conventional ``-0000`` is used for the timezone. 171 If it is an aware ``datetime``, then the numeric timezone offset is used. 172 If it is an aware timezone with offset zero, then *usegmt* may be set to 173 ``True``, in which case the string ``GMT`` is used instead of the numeric 174 timezone offset. This provides a way to generate standards conformant HTTP 175 date headers. 176 177 .. versionadded:: 3.3 178 179 180.. function:: decode_rfc2231(s) 181 182 Decode the string *s* according to :rfc:`2231`. 183 184 185.. function:: encode_rfc2231(s, charset=None, language=None) 186 187 Encode the string *s* according to :rfc:`2231`. Optional *charset* and 188 *language*, if given is the character set name and language name to use. If 189 neither is given, *s* is returned as-is. If *charset* is given but *language* 190 is not, the string is encoded using the empty string for *language*. 191 192 193.. function:: collapse_rfc2231_value(value, errors='replace', fallback_charset='us-ascii') 194 195 When a header parameter is encoded in :rfc:`2231` format, 196 :meth:`Message.get_param <email.message.Message.get_param>` may return a 197 3-tuple containing the character set, 198 language, and value. :func:`collapse_rfc2231_value` turns this into a unicode 199 string. Optional *errors* is passed to the *errors* argument of :class:`str`'s 200 :func:`~str.encode` method; it defaults to ``'replace'``. Optional 201 *fallback_charset* specifies the character set to use if the one in the 202 :rfc:`2231` header is not known by Python; it defaults to ``'us-ascii'``. 203 204 For convenience, if the *value* passed to :func:`collapse_rfc2231_value` is not 205 a tuple, it should be a string and it is returned unquoted. 206 207 208.. function:: decode_params(params) 209 210 Decode parameters list according to :rfc:`2231`. *params* is a sequence of 211 2-tuples containing elements of the form ``(content-type, string-value)``. 212 213 214.. rubric:: Footnotes 215 216.. [#] Note that the sign of the timezone offset is the opposite of the sign of the 217 ``time.timezone`` variable for the same timezone; the latter variable follows 218 the POSIX standard while this module follows :rfc:`2822`. 219