1:mod:`email.utils`: Miscellaneous utilities
2-------------------------------------------
3
4.. module:: email.utils
5   :synopsis: Miscellaneous email package utilities.
6
7
8There are several useful utilities provided in the :mod:`email.utils` module:
9
10
11.. function:: quote(str)
12
13   Return a new string with backslashes in *str* replaced by two backslashes, and
14   double quotes replaced by backslash-double quote.
15
16
17.. function:: unquote(str)
18
19   Return a new string which is an *unquoted* version of *str*. If *str* ends and
20   begins with double quotes, they are stripped off.  Likewise if *str* ends and
21   begins with angle brackets, they are stripped off.
22
23
24.. function:: parseaddr(address)
25
26   Parse address -- which should be the value of some address-containing field such
27   as :mailheader:`To` or :mailheader:`Cc` -- into its constituent *realname* and
28   *email address* parts.  Returns a tuple of that information, unless the parse
29   fails, in which case a 2-tuple of ``('', '')`` is returned.
30
31
32.. function:: formataddr(pair)
33
34   The inverse of :meth:`parseaddr`, this takes a 2-tuple of the form ``(realname,
35   email_address)`` and returns the string value suitable for a :mailheader:`To` or
36   :mailheader:`Cc` header.  If the first element of *pair* is false, then the
37   second element is returned unmodified.
38
39
40.. function:: getaddresses(fieldvalues)
41
42   This method returns a list of 2-tuples of the form returned by ``parseaddr()``.
43   *fieldvalues* is a sequence of header field values as might be returned by
44   :meth:`Message.get_all <email.message.Message.get_all>`.  Here's a simple
45   example that gets all the recipients of a message::
46
47      from email.utils import getaddresses
48
49      tos = msg.get_all('to', [])
50      ccs = msg.get_all('cc', [])
51      resent_tos = msg.get_all('resent-to', [])
52      resent_ccs = msg.get_all('resent-cc', [])
53      all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)
54
55
56.. function:: parsedate(date)
57
58   Attempts to parse a date according to the rules in :rfc:`2822`. however, some
59   mailers don't follow that format as specified, so :func:`parsedate` tries to
60   guess correctly in such cases.  *date* is a string containing an :rfc:`2822`
61   date, such as  ``"Mon, 20 Nov 1995 19:12:08 -0500"``.  If it succeeds in parsing
62   the date, :func:`parsedate` returns a 9-tuple that can be passed directly to
63   :func:`time.mktime`; otherwise ``None`` will be returned.  Note that indexes 6,
64   7, and 8 of the result tuple are not usable.
65
66
67.. function:: parsedate_tz(date)
68
69   Performs the same function as :func:`parsedate`, but returns either ``None`` or
70   a 10-tuple; the first 9 elements make up a tuple that can be passed directly to
71   :func:`time.mktime`, and the tenth is the offset of the date's timezone from UTC
72   (which is the official term for Greenwich Mean Time) [#]_.  If the input string
73   has no timezone, the last element of the tuple returned is ``None``.  Note that
74   indexes 6, 7, and 8 of the result tuple are not usable.
75
76
77.. function:: mktime_tz(tuple)
78
79   Turn a 10-tuple as returned by :func:`parsedate_tz` into a UTC
80   timestamp (seconds since the Epoch).  If the timezone item in the
81   tuple is ``None``, assume local time.
82
83
84.. function:: formatdate([timeval[, localtime][, usegmt]])
85
86   Returns a date string as per :rfc:`2822`, e.g.::
87
88      Fri, 09 Nov 2001 01:08:47 -0000
89
90   Optional *timeval* if given is a floating point time value as accepted by
91   :func:`time.gmtime` and :func:`time.localtime`, otherwise the current time is
92   used.
93
94   Optional *localtime* is a flag that when ``True``, interprets *timeval*, and
95   returns a date relative to the local timezone instead of UTC, properly taking
96   daylight savings time into account. The default is ``False`` meaning UTC is
97   used.
98
99   Optional *usegmt* is a flag that when ``True``, outputs a  date string with the
100   timezone as an ascii string ``GMT``, rather than a numeric ``-0000``. This is
101   needed for some protocols (such as HTTP). This only applies when *localtime* is
102   ``False``.  The default is ``False``.
103
104   .. versionadded:: 2.4
105
106
107.. function:: make_msgid([idstring])
108
109   Returns a string suitable for an :rfc:`2822`\ -compliant
110   :mailheader:`Message-ID` header.  Optional *idstring* if given, is a string used
111   to strengthen the uniqueness of the message id.
112
113
114.. function:: decode_rfc2231(s)
115
116   Decode the string *s* according to :rfc:`2231`.
117
118
119.. function:: encode_rfc2231(s[, charset[, language]])
120
121   Encode the string *s* according to :rfc:`2231`.  Optional *charset* and
122   *language*, if given is the character set name and language name to use.  If
123   neither is given, *s* is returned as-is.  If *charset* is given but *language*
124   is not, the string is encoded using the empty string for *language*.
125
126
127.. function:: collapse_rfc2231_value(value[, errors[, fallback_charset]])
128
129   When a header parameter is encoded in :rfc:`2231` format,
130   :meth:`Message.get_param <email.message.Message.get_param>` may return a
131   3-tuple containing the character set,
132   language, and value.  :func:`collapse_rfc2231_value` turns this into a unicode
133   string.  Optional *errors* is passed to the *errors* argument of the built-in
134   :func:`unicode` function; it defaults to ``replace``.  Optional
135   *fallback_charset* specifies the character set to use if the one in the
136   :rfc:`2231` header is not known by Python; it defaults to ``us-ascii``.
137
138   For convenience, if the *value* passed to :func:`collapse_rfc2231_value` is not
139   a tuple, it should be a string and it is returned unquoted.
140
141
142.. function:: decode_params(params)
143
144   Decode parameters list according to :rfc:`2231`.  *params* is a sequence of
145   2-tuples containing elements of the form ``(content-type, string-value)``.
146
147.. versionchanged:: 2.4
148   The :func:`dump_address_pair` function has been removed; use :func:`formataddr`
149   instead.
150
151.. versionchanged:: 2.4
152   The :func:`decode` function has been removed; use the
153   :meth:`Header.decode_header <email.header.Header.decode_header>` method
154   instead.
155
156.. versionchanged:: 2.4
157   The :func:`encode` function has been removed; use the :meth:`Header.encode
158   <email.header.Header.encode>` method instead.
159
160.. rubric:: Footnotes
161
162.. [#] Note that the sign of the timezone offset is the opposite of the sign of the
163   ``time.timezone`` variable for the same timezone; the latter variable follows
164   the POSIX standard while this module follows :rfc:`2822`.
165