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, *, strict=True) 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 If *strict* is true, use a strict parser which rejects malformed inputs. 71 72 .. versionchanged:: 3.13 73 Add *strict* optional parameter and reject malformed inputs by default. 74 75 76 77.. function:: formataddr(pair, charset='utf-8') 78 79 The inverse of :meth:`parseaddr`, this takes a 2-tuple of the form ``(realname, 80 email_address)`` and returns the string value suitable for a :mailheader:`To` or 81 :mailheader:`Cc` header. If the first element of *pair* is false, then the 82 second element is returned unmodified. 83 84 Optional *charset* is the character set that will be used in the :rfc:`2047` 85 encoding of the ``realname`` if the ``realname`` contains non-ASCII 86 characters. Can be an instance of :class:`str` or a 87 :class:`~email.charset.Charset`. Defaults to ``utf-8``. 88 89 .. versionchanged:: 3.3 90 Added the *charset* option. 91 92 93.. function:: getaddresses(fieldvalues, *, strict=True) 94 95 This method returns a list of 2-tuples of the form returned by ``parseaddr()``. 96 *fieldvalues* is a sequence of header field values as might be returned by 97 :meth:`Message.get_all <email.message.Message.get_all>`. 98 99 If *strict* is true, use a strict parser which rejects malformed inputs. 100 101 Here's a simple example that gets all the recipients of a message:: 102 103 from email.utils import getaddresses 104 105 tos = msg.get_all('to', []) 106 ccs = msg.get_all('cc', []) 107 resent_tos = msg.get_all('resent-to', []) 108 resent_ccs = msg.get_all('resent-cc', []) 109 all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs) 110 111 .. versionchanged:: 3.13 112 Add *strict* optional parameter and reject malformed inputs by default. 113 114 115.. function:: parsedate(date) 116 117 Attempts to parse a date according to the rules in :rfc:`2822`. however, some 118 mailers don't follow that format as specified, so :func:`parsedate` tries to 119 guess correctly in such cases. *date* is a string containing an :rfc:`2822` 120 date, such as ``"Mon, 20 Nov 1995 19:12:08 -0500"``. If it succeeds in parsing 121 the date, :func:`parsedate` returns a 9-tuple that can be passed directly to 122 :func:`time.mktime`; otherwise ``None`` will be returned. Note that indexes 6, 123 7, and 8 of the result tuple are not usable. 124 125 126.. function:: parsedate_tz(date) 127 128 Performs the same function as :func:`parsedate`, but returns either ``None`` or 129 a 10-tuple; the first 9 elements make up a tuple that can be passed directly to 130 :func:`time.mktime`, and the tenth is the offset of the date's timezone from UTC 131 (which is the official term for Greenwich Mean Time) [#]_. If the input string 132 has no timezone, the last element of the tuple returned is ``0``, which represents 133 UTC. Note that indexes 6, 7, and 8 of the result tuple are not usable. 134 135 136.. function:: parsedate_to_datetime(date) 137 138 The inverse of :func:`format_datetime`. Performs the same function as 139 :func:`parsedate`, but on success returns a :mod:`~datetime.datetime`; 140 otherwise ``ValueError`` is raised if *date* contains an invalid value such 141 as an hour greater than 23 or a timezone offset not between -24 and 24 hours. 142 If the input date has a timezone of ``-0000``, the ``datetime`` will be a naive 143 ``datetime``, and if the date is conforming to the RFCs it will represent a 144 time in UTC but with no indication of the actual source timezone of the 145 message the date comes from. If the input date has any other valid timezone 146 offset, the ``datetime`` will be an aware ``datetime`` with the 147 corresponding a :class:`~datetime.timezone` :class:`~datetime.tzinfo`. 148 149 .. versionadded:: 3.3 150 151 152.. function:: mktime_tz(tuple) 153 154 Turn a 10-tuple as returned by :func:`parsedate_tz` into a UTC 155 timestamp (seconds since the Epoch). If the timezone item in the 156 tuple is ``None``, assume local time. 157 158 159.. function:: formatdate(timeval=None, localtime=False, usegmt=False) 160 161 Returns a date string as per :rfc:`2822`, e.g.:: 162 163 Fri, 09 Nov 2001 01:08:47 -0000 164 165 Optional *timeval* if given is a floating point time value as accepted by 166 :func:`time.gmtime` and :func:`time.localtime`, otherwise the current time is 167 used. 168 169 Optional *localtime* is a flag that when ``True``, interprets *timeval*, and 170 returns a date relative to the local timezone instead of UTC, properly taking 171 daylight savings time into account. The default is ``False`` meaning UTC is 172 used. 173 174 Optional *usegmt* is a flag that when ``True``, outputs a date string with the 175 timezone as an ascii string ``GMT``, rather than a numeric ``-0000``. This is 176 needed for some protocols (such as HTTP). This only applies when *localtime* is 177 ``False``. The default is ``False``. 178 179 180.. function:: format_datetime(dt, usegmt=False) 181 182 Like ``formatdate``, but the input is a :mod:`datetime` instance. If it is 183 a naive datetime, it is assumed to be "UTC with no information about the 184 source timezone", and the conventional ``-0000`` is used for the timezone. 185 If it is an aware ``datetime``, then the numeric timezone offset is used. 186 If it is an aware timezone with offset zero, then *usegmt* may be set to 187 ``True``, in which case the string ``GMT`` is used instead of the numeric 188 timezone offset. This provides a way to generate standards conformant HTTP 189 date headers. 190 191 .. versionadded:: 3.3 192 193 194.. function:: decode_rfc2231(s) 195 196 Decode the string *s* according to :rfc:`2231`. 197 198 199.. function:: encode_rfc2231(s, charset=None, language=None) 200 201 Encode the string *s* according to :rfc:`2231`. Optional *charset* and 202 *language*, if given is the character set name and language name to use. If 203 neither is given, *s* is returned as-is. If *charset* is given but *language* 204 is not, the string is encoded using the empty string for *language*. 205 206 207.. function:: collapse_rfc2231_value(value, errors='replace', fallback_charset='us-ascii') 208 209 When a header parameter is encoded in :rfc:`2231` format, 210 :meth:`Message.get_param <email.message.Message.get_param>` may return a 211 3-tuple containing the character set, 212 language, and value. :func:`collapse_rfc2231_value` turns this into a unicode 213 string. Optional *errors* is passed to the *errors* argument of :class:`str`'s 214 :func:`~str.encode` method; it defaults to ``'replace'``. Optional 215 *fallback_charset* specifies the character set to use if the one in the 216 :rfc:`2231` header is not known by Python; it defaults to ``'us-ascii'``. 217 218 For convenience, if the *value* passed to :func:`collapse_rfc2231_value` is not 219 a tuple, it should be a string and it is returned unquoted. 220 221 222.. function:: decode_params(params) 223 224 Decode parameters list according to :rfc:`2231`. *params* is a sequence of 225 2-tuples containing elements of the form ``(content-type, string-value)``. 226 227 228.. rubric:: Footnotes 229 230.. [#] Note that the sign of the timezone offset is the opposite of the sign of the 231 ``time.timezone`` variable for the same timezone; the latter variable follows 232 the POSIX standard while this module follows :rfc:`2822`. 233