1:mod:`email.iterators`: Iterators
2---------------------------------
3
4.. module:: email.iterators
5   :synopsis: Iterate over a  message object tree.
6
7**Source code:** :source:`Lib/email/iterators.py`
8
9--------------
10
11Iterating over a message object tree is fairly easy with the
12:meth:`Message.walk <email.message.Message.walk>` method.  The
13:mod:`email.iterators` module provides some useful higher level iterations over
14message object trees.
15
16
17.. function:: body_line_iterator(msg, decode=False)
18
19   This iterates over all the payloads in all the subparts of *msg*, returning the
20   string payloads line-by-line.  It skips over all the subpart headers, and it
21   skips over any subpart with a payload that isn't a Python string.  This is
22   somewhat equivalent to reading the flat text representation of the message from
23   a file using :meth:`~io.TextIOBase.readline`, skipping over all the
24   intervening headers.
25
26   Optional *decode* is passed through to :meth:`Message.get_payload
27   <email.message.Message.get_payload>`.
28
29
30.. function:: typed_subpart_iterator(msg, maintype='text', subtype=None)
31
32   This iterates over all the subparts of *msg*, returning only those subparts that
33   match the MIME type specified by *maintype* and *subtype*.
34
35   Note that *subtype* is optional; if omitted, then subpart MIME type matching is
36   done only with the main type.  *maintype* is optional too; it defaults to
37   :mimetype:`text`.
38
39   Thus, by default :func:`typed_subpart_iterator` returns each subpart that has a
40   MIME type of :mimetype:`text/\*`.
41
42
43The following function has been added as a useful debugging tool.  It should
44*not* be considered part of the supported public interface for the package.
45
46.. function:: _structure(msg, fp=None, level=0, include_default=False)
47
48   Prints an indented representation of the content types of the message object
49   structure.  For example:
50
51   .. testsetup::
52
53      import email
54      from email.iterators import _structure
55      somefile = open('../Lib/test/test_email/data/msg_02.txt')
56
57   .. doctest::
58
59      >>> msg = email.message_from_file(somefile)
60      >>> _structure(msg)
61      multipart/mixed
62          text/plain
63          text/plain
64          multipart/digest
65              message/rfc822
66                  text/plain
67              message/rfc822
68                  text/plain
69              message/rfc822
70                  text/plain
71              message/rfc822
72                  text/plain
73              message/rfc822
74                  text/plain
75          text/plain
76
77   .. testcleanup::
78
79      somefile.close()
80
81   Optional *fp* is a file-like object to print the output to.  It must be
82   suitable for Python's :func:`print` function.  *level* is used internally.
83   *include_default*, if true, prints the default type as well.
84