mirror of https://github.com/python/cpython
531 lines
22 KiB
ReStructuredText
531 lines
22 KiB
ReStructuredText
:mod:`email`: Representing an email message
|
|
-------------------------------------------
|
|
|
|
.. module:: email.message
|
|
:synopsis: The base class representing email messages.
|
|
|
|
|
|
The central class in the :mod:`email` package is the :class:`Message` class,
|
|
imported from the :mod:`email.message` module. It is the base class for the
|
|
:mod:`email` object model. :class:`Message` provides the core functionality for
|
|
setting and querying header fields, and for accessing message bodies.
|
|
|
|
Conceptually, a :class:`Message` object consists of *headers* and *payloads*.
|
|
Headers are :rfc:`2822` style field names and values where the field name and
|
|
value are separated by a colon. The colon is not part of either the field name
|
|
or the field value.
|
|
|
|
Headers are stored and returned in case-preserving form but are matched
|
|
case-insensitively. There may also be a single envelope header, also known as
|
|
the *Unix-From* header or the ``From_`` header. The payload is either a string
|
|
in the case of simple message objects or a list of :class:`Message` objects for
|
|
MIME container documents (e.g. :mimetype:`multipart/\*` and
|
|
:mimetype:`message/rfc822`).
|
|
|
|
:class:`Message` objects provide a mapping style interface for accessing the
|
|
message headers, and an explicit interface for accessing both the headers and
|
|
the payload. It provides convenience methods for generating a flat text
|
|
representation of the message object tree, for accessing commonly used header
|
|
parameters, and for recursively walking over the object tree.
|
|
|
|
Here are the methods of the :class:`Message` class:
|
|
|
|
|
|
.. class:: Message()
|
|
|
|
The constructor takes no arguments.
|
|
|
|
|
|
.. method:: as_string(unixfrom=False, maxheaderlen=0)
|
|
|
|
Return the entire message flattened as a string. When optional *unixfrom*
|
|
is ``True``, the envelope header is included in the returned string.
|
|
*unixfrom* defaults to ``False``. Flattening the message may trigger
|
|
changes to the :class:`Message` if defaults need to be filled in to
|
|
complete the transformation to a string (for example, MIME boundaries may
|
|
be generated or modified).
|
|
|
|
Note that this method is provided as a convenience and may not always
|
|
format the message the way you want. For example, by default it mangles
|
|
lines that begin with ``From``. For more flexibility, instantiate a
|
|
:class:`~email.generator.Generator` instance and use its :meth:`flatten`
|
|
method directly. For example::
|
|
|
|
from io import StringIO
|
|
from email.generator import Generator
|
|
fp = StringIO()
|
|
g = Generator(fp, mangle_from_=False, maxheaderlen=60)
|
|
g.flatten(msg)
|
|
text = fp.getvalue()
|
|
|
|
|
|
.. method:: __str__()
|
|
|
|
Equivalent to ``as_string(unixfrom=True)``.
|
|
|
|
|
|
.. method:: is_multipart()
|
|
|
|
Return ``True`` if the message's payload is a list of sub-\
|
|
:class:`Message` objects, otherwise return ``False``. When
|
|
:meth:`is_multipart` returns False, the payload should be a string object.
|
|
|
|
|
|
.. method:: set_unixfrom(unixfrom)
|
|
|
|
Set the message's envelope header to *unixfrom*, which should be a string.
|
|
|
|
|
|
.. method:: get_unixfrom()
|
|
|
|
Return the message's envelope header. Defaults to ``None`` if the
|
|
envelope header was never set.
|
|
|
|
|
|
.. method:: attach(payload)
|
|
|
|
Add the given *payload* to the current payload, which must be ``None`` or
|
|
a list of :class:`Message` objects before the call. After the call, the
|
|
payload will always be a list of :class:`Message` objects. If you want to
|
|
set the payload to a scalar object (e.g. a string), use
|
|
:meth:`set_payload` instead.
|
|
|
|
|
|
.. method:: get_payload(i=None, decode=False)
|
|
|
|
Return the current payload, which will be a list of
|
|
:class:`Message` objects when :meth:`is_multipart` is ``True``, or a
|
|
string when :meth:`is_multipart` is ``False``. If the payload is a list
|
|
and you mutate the list object, you modify the message's payload in place.
|
|
|
|
With optional argument *i*, :meth:`get_payload` will return the *i*-th
|
|
element of the payload, counting from zero, if :meth:`is_multipart` is
|
|
``True``. An :exc:`IndexError` will be raised if *i* is less than 0 or
|
|
greater than or equal to the number of items in the payload. If the
|
|
payload is a string (i.e. :meth:`is_multipart` is ``False``) and *i* is
|
|
given, a :exc:`TypeError` is raised.
|
|
|
|
Optional *decode* is a flag indicating whether the payload should be
|
|
decoded or not, according to the :mailheader:`Content-Transfer-Encoding`
|
|
header. When ``True`` and the message is not a multipart, the payload will
|
|
be decoded if this header's value is ``quoted-printable`` or ``base64``.
|
|
If some other encoding is used, or :mailheader:`Content-Transfer-Encoding`
|
|
header is missing, or if the payload has bogus base64 data, the payload is
|
|
returned as-is (undecoded). If the message is a multipart and the
|
|
*decode* flag is ``True``, then ``None`` is returned. The default for
|
|
*decode* is ``False``.
|
|
|
|
|
|
.. method:: set_payload(payload, charset=None)
|
|
|
|
Set the entire message object's payload to *payload*. It is the client's
|
|
responsibility to ensure the payload invariants. Optional *charset* sets
|
|
the message's default character set; see :meth:`set_charset` for details.
|
|
|
|
.. method:: set_charset(charset)
|
|
|
|
Set the character set of the payload to *charset*, which can either be a
|
|
:class:`~email.charset.Charset` instance (see :mod:`email.charset`), a
|
|
string naming a character set, or ``None``. If it is a string, it will
|
|
be converted to a :class:`~email.charset.Charset` instance. If *charset*
|
|
is ``None``, the ``charset`` parameter will be removed from the
|
|
:mailheader:`Content-Type` header. Anything else will generate a
|
|
:exc:`TypeError`.
|
|
|
|
The message will be assumed to be of type :mimetype:`text/\*` encoded with
|
|
*charset.input_charset*. It will be converted to *charset.output_charset*
|
|
and encoded properly, if needed, when generating the plain text
|
|
representation of the message. MIME headers (:mailheader:`MIME-Version`,
|
|
:mailheader:`Content-Type`, :mailheader:`Content-Transfer-Encoding`) will
|
|
be added as needed.
|
|
|
|
.. method:: get_charset()
|
|
|
|
Return the :class:`~email.charset.Charset` instance associated with the
|
|
message's payload.
|
|
|
|
The following methods implement a mapping-like interface for accessing the
|
|
message's :rfc:`2822` headers. Note that there are some semantic differences
|
|
between these methods and a normal mapping (i.e. dictionary) interface. For
|
|
example, in a dictionary there are no duplicate keys, but here there may be
|
|
duplicate message headers. Also, in dictionaries there is no guaranteed
|
|
order to the keys returned by :meth:`keys`, but in a :class:`Message` object,
|
|
headers are always returned in the order they appeared in the original
|
|
message, or were added to the message later. Any header deleted and then
|
|
re-added are always appended to the end of the header list.
|
|
|
|
These semantic differences are intentional and are biased toward maximal
|
|
convenience.
|
|
|
|
Note that in all cases, any envelope header present in the message is not
|
|
included in the mapping interface.
|
|
|
|
|
|
.. method:: __len__()
|
|
|
|
Return the total number of headers, including duplicates.
|
|
|
|
|
|
.. method:: __contains__(name)
|
|
|
|
Return true if the message object has a field named *name*. Matching is
|
|
done case-insensitively and *name* should not include the trailing colon.
|
|
Used for the ``in`` operator, e.g.::
|
|
|
|
if 'message-id' in myMessage:
|
|
print('Message-ID:', myMessage['message-id'])
|
|
|
|
|
|
.. method:: __getitem__(name)
|
|
|
|
Return the value of the named header field. *name* should not include the
|
|
colon field separator. If the header is missing, ``None`` is returned; a
|
|
:exc:`KeyError` is never raised.
|
|
|
|
Note that if the named field appears more than once in the message's
|
|
headers, exactly which of those field values will be returned is
|
|
undefined. Use the :meth:`get_all` method to get the values of all the
|
|
extant named headers.
|
|
|
|
|
|
.. method:: __setitem__(name, val)
|
|
|
|
Add a header to the message with field name *name* and value *val*. The
|
|
field is appended to the end of the message's existing fields.
|
|
|
|
Note that this does *not* overwrite or delete any existing header with the same
|
|
name. If you want to ensure that the new header is the only one present in the
|
|
message with field name *name*, delete the field first, e.g.::
|
|
|
|
del msg['subject']
|
|
msg['subject'] = 'Python roolz!'
|
|
|
|
|
|
.. method:: __delitem__(name)
|
|
|
|
Delete all occurrences of the field with name *name* from the message's
|
|
headers. No exception is raised if the named field isn't present in the
|
|
headers.
|
|
|
|
|
|
.. method:: Message.__contains__(name)
|
|
|
|
Return true if the message contains a header field named *name*, otherwise
|
|
return false.
|
|
|
|
|
|
.. method:: keys()
|
|
|
|
Return a list of all the message's header field names.
|
|
|
|
|
|
.. method:: values()
|
|
|
|
Return a list of all the message's field values.
|
|
|
|
|
|
.. method:: items()
|
|
|
|
Return a list of 2-tuples containing all the message's field headers and
|
|
values.
|
|
|
|
|
|
.. method:: get(name, failobj=None)
|
|
|
|
Return the value of the named header field. This is identical to
|
|
:meth:`__getitem__` except that optional *failobj* is returned if the
|
|
named header is missing (defaults to ``None``).
|
|
|
|
Here are some additional useful methods:
|
|
|
|
|
|
.. method:: get_all(name, failobj=None)
|
|
|
|
Return a list of all the values for the field named *name*. If there are
|
|
no such named headers in the message, *failobj* is returned (defaults to
|
|
``None``).
|
|
|
|
|
|
.. method:: add_header(_name, _value, **_params)
|
|
|
|
Extended header setting. This method is similar to :meth:`__setitem__`
|
|
except that additional header parameters can be provided as keyword
|
|
arguments. *_name* is the header field to add and *_value* is the
|
|
*primary* value for the header.
|
|
|
|
For each item in the keyword argument dictionary *_params*, the key is
|
|
taken as the parameter name, with underscores converted to dashes (since
|
|
dashes are illegal in Python identifiers). Normally, the parameter will
|
|
be added as ``key="value"`` unless the value is ``None``, in which case
|
|
only the key will be added.
|
|
|
|
Here's an example::
|
|
|
|
msg.add_header('Content-Disposition', 'attachment', filename='bud.gif')
|
|
|
|
This will add a header that looks like ::
|
|
|
|
Content-Disposition: attachment; filename="bud.gif"
|
|
|
|
|
|
.. method:: replace_header(_name, _value)
|
|
|
|
Replace a header. Replace the first header found in the message that
|
|
matches *_name*, retaining header order and field name case. If no
|
|
matching header was found, a :exc:`KeyError` is raised.
|
|
|
|
|
|
.. method:: get_content_type()
|
|
|
|
Return the message's content type. The returned string is coerced to
|
|
lower case of the form :mimetype:`maintype/subtype`. If there was no
|
|
:mailheader:`Content-Type` header in the message the default type as given
|
|
by :meth:`get_default_type` will be returned. Since according to
|
|
:rfc:`2045`, messages always have a default type, :meth:`get_content_type`
|
|
will always return a value.
|
|
|
|
:rfc:`2045` defines a message's default type to be :mimetype:`text/plain`
|
|
unless it appears inside a :mimetype:`multipart/digest` container, in
|
|
which case it would be :mimetype:`message/rfc822`. If the
|
|
:mailheader:`Content-Type` header has an invalid type specification,
|
|
:rfc:`2045` mandates that the default type be :mimetype:`text/plain`.
|
|
|
|
|
|
.. method:: get_content_maintype()
|
|
|
|
Return the message's main content type. This is the :mimetype:`maintype`
|
|
part of the string returned by :meth:`get_content_type`.
|
|
|
|
|
|
.. method:: get_content_subtype()
|
|
|
|
Return the message's sub-content type. This is the :mimetype:`subtype`
|
|
part of the string returned by :meth:`get_content_type`.
|
|
|
|
|
|
.. method:: get_default_type()
|
|
|
|
Return the default content type. Most messages have a default content
|
|
type of :mimetype:`text/plain`, except for messages that are subparts of
|
|
:mimetype:`multipart/digest` containers. Such subparts have a default
|
|
content type of :mimetype:`message/rfc822`.
|
|
|
|
|
|
.. method:: set_default_type(ctype)
|
|
|
|
Set the default content type. *ctype* should either be
|
|
:mimetype:`text/plain` or :mimetype:`message/rfc822`, although this is not
|
|
enforced. The default content type is not stored in the
|
|
:mailheader:`Content-Type` header.
|
|
|
|
|
|
.. method:: get_params(failobj=None, header='content-type', unquote=True)
|
|
|
|
Return the message's :mailheader:`Content-Type` parameters, as a list.
|
|
The elements of the returned list are 2-tuples of key/value pairs, as
|
|
split on the ``'='`` sign. The left hand side of the ``'='`` is the key,
|
|
while the right hand side is the value. If there is no ``'='`` sign in
|
|
the parameter the value is the empty string, otherwise the value is as
|
|
described in :meth:`get_param` and is unquoted if optional *unquote* is
|
|
``True`` (the default).
|
|
|
|
Optional *failobj* is the object to return if there is no
|
|
:mailheader:`Content-Type` header. Optional *header* is the header to
|
|
search instead of :mailheader:`Content-Type`.
|
|
|
|
|
|
.. method:: get_param(param, failobj=None, header='content-type', unquote=True)
|
|
|
|
Return the value of the :mailheader:`Content-Type` header's parameter
|
|
*param* as a string. If the message has no :mailheader:`Content-Type`
|
|
header or if there is no such parameter, then *failobj* is returned
|
|
(defaults to ``None``).
|
|
|
|
Optional *header* if given, specifies the message header to use instead of
|
|
:mailheader:`Content-Type`.
|
|
|
|
Parameter keys are always compared case insensitively. The return value
|
|
can either be a string, or a 3-tuple if the parameter was :rfc:`2231`
|
|
encoded. When it's a 3-tuple, the elements of the value are of the form
|
|
``(CHARSET, LANGUAGE, VALUE)``. Note that both ``CHARSET`` and
|
|
``LANGUAGE`` can be ``None``, in which case you should consider ``VALUE``
|
|
to be encoded in the ``us-ascii`` charset. You can usually ignore
|
|
``LANGUAGE``.
|
|
|
|
If your application doesn't care whether the parameter was encoded as in
|
|
:rfc:`2231`, you can collapse the parameter value by calling
|
|
:func:`email.utils.collapse_rfc2231_value`, passing in the return value
|
|
from :meth:`get_param`. This will return a suitably decoded Unicode
|
|
string whn the value is a tuple, or the original string unquoted if it
|
|
isn't. For example::
|
|
|
|
rawparam = msg.get_param('foo')
|
|
param = email.utils.collapse_rfc2231_value(rawparam)
|
|
|
|
In any case, the parameter value (either the returned string, or the
|
|
``VALUE`` item in the 3-tuple) is always unquoted, unless *unquote* is set
|
|
to ``False``.
|
|
|
|
|
|
.. method:: set_param(param, value, header='Content-Type', requote=True, charset=None, language='')
|
|
|
|
Set a parameter in the :mailheader:`Content-Type` header. If the
|
|
parameter already exists in the header, its value will be replaced with
|
|
*value*. If the :mailheader:`Content-Type` header as not yet been defined
|
|
for this message, it will be set to :mimetype:`text/plain` and the new
|
|
parameter value will be appended as per :rfc:`2045`.
|
|
|
|
Optional *header* specifies an alternative header to
|
|
:mailheader:`Content-Type`, and all parameters will be quoted as necessary
|
|
unless optional *requote* is ``False`` (the default is ``True``).
|
|
|
|
If optional *charset* is specified, the parameter will be encoded
|
|
according to :rfc:`2231`. Optional *language* specifies the RFC 2231
|
|
language, defaulting to the empty string. Both *charset* and *language*
|
|
should be strings.
|
|
|
|
|
|
.. method:: del_param(param, header='content-type', requote=True)
|
|
|
|
Remove the given parameter completely from the :mailheader:`Content-Type`
|
|
header. The header will be re-written in place without the parameter or
|
|
its value. All values will be quoted as necessary unless *requote* is
|
|
``False`` (the default is ``True``). Optional *header* specifies an
|
|
alternative to :mailheader:`Content-Type`.
|
|
|
|
|
|
.. method:: set_type(type, header='Content-Type', requote=True)
|
|
|
|
Set the main type and subtype for the :mailheader:`Content-Type`
|
|
header. *type* must be a string in the form :mimetype:`maintype/subtype`,
|
|
otherwise a :exc:`ValueError` is raised.
|
|
|
|
This method replaces the :mailheader:`Content-Type` header, keeping all
|
|
the parameters in place. If *requote* is ``False``, this leaves the
|
|
existing header's quoting as is, otherwise the parameters will be quoted
|
|
(the default).
|
|
|
|
An alternative header can be specified in the *header* argument. When the
|
|
:mailheader:`Content-Type` header is set a :mailheader:`MIME-Version`
|
|
header is also added.
|
|
|
|
|
|
.. method:: get_filename(failobj=None)
|
|
|
|
Return the value of the ``filename`` parameter of the
|
|
:mailheader:`Content-Disposition` header of the message. If the header
|
|
does not have a ``filename`` parameter, this method falls back to looking
|
|
for the ``name`` parameter. If neither is found, or the header is
|
|
missing, then *failobj* is returned. The returned string will always be
|
|
unquoted as per :func:`email.utils.unquote`.
|
|
|
|
|
|
.. method:: get_boundary(failobj=None)
|
|
|
|
Return the value of the ``boundary`` parameter of the
|
|
:mailheader:`Content-Type` header of the message, or *failobj* if either
|
|
the header is missing, or has no ``boundary`` parameter. The returned
|
|
string will always be unquoted as per :func:`email.utils.unquote`.
|
|
|
|
|
|
.. method:: set_boundary(boundary)
|
|
|
|
Set the ``boundary`` parameter of the :mailheader:`Content-Type` header to
|
|
*boundary*. :meth:`set_boundary` will always quote *boundary* if
|
|
necessary. A :exc:`HeaderParseError` is raised if the message object has
|
|
no :mailheader:`Content-Type` header.
|
|
|
|
Note that using this method is subtly different than deleting the old
|
|
:mailheader:`Content-Type` header and adding a new one with the new
|
|
boundary via :meth:`add_header`, because :meth:`set_boundary` preserves
|
|
the order of the :mailheader:`Content-Type` header in the list of
|
|
headers. However, it does *not* preserve any continuation lines which may
|
|
have been present in the original :mailheader:`Content-Type` header.
|
|
|
|
|
|
.. method:: get_content_charset(failobj=None)
|
|
|
|
Return the ``charset`` parameter of the :mailheader:`Content-Type` header,
|
|
coerced to lower case. If there is no :mailheader:`Content-Type` header, or if
|
|
that header has no ``charset`` parameter, *failobj* is returned.
|
|
|
|
Note that this method differs from :meth:`get_charset` which returns the
|
|
:class:`~email.charset.Charset` instance for the default encoding of the message body.
|
|
|
|
|
|
.. method:: get_charsets(failobj=None)
|
|
|
|
Return a list containing the character set names in the message. If the
|
|
message is a :mimetype:`multipart`, then the list will contain one element
|
|
for each subpart in the payload, otherwise, it will be a list of length 1.
|
|
|
|
Each item in the list will be a string which is the value of the
|
|
``charset`` parameter in the :mailheader:`Content-Type` header for the
|
|
represented subpart. However, if the subpart has no
|
|
:mailheader:`Content-Type` header, no ``charset`` parameter, or is not of
|
|
the :mimetype:`text` main MIME type, then that item in the returned list
|
|
will be *failobj*.
|
|
|
|
|
|
.. method:: walk()
|
|
|
|
The :meth:`walk` method is an all-purpose generator which can be used to
|
|
iterate over all the parts and subparts of a message object tree, in
|
|
depth-first traversal order. You will typically use :meth:`walk` as the
|
|
iterator in a ``for`` loop; each iteration returns the next subpart.
|
|
|
|
Here's an example that prints the MIME type of every part of a multipart
|
|
message structure::
|
|
|
|
>>> for part in msg.walk():
|
|
... print(part.get_content_type())
|
|
multipart/report
|
|
text/plain
|
|
message/delivery-status
|
|
text/plain
|
|
text/plain
|
|
message/rfc822
|
|
|
|
:class:`Message` objects can also optionally contain two instance attributes,
|
|
which can be used when generating the plain text of a MIME message.
|
|
|
|
|
|
.. attribute:: preamble
|
|
|
|
The format of a MIME document allows for some text between the blank line
|
|
following the headers, and the first multipart boundary string. Normally,
|
|
this text is never visible in a MIME-aware mail reader because it falls
|
|
outside the standard MIME armor. However, when viewing the raw text of
|
|
the message, or when viewing the message in a non-MIME aware reader, this
|
|
text can become visible.
|
|
|
|
The *preamble* attribute contains this leading extra-armor text for MIME
|
|
documents. When the :class:`~email.parser.Parser` discovers some text
|
|
after the headers but before the first boundary string, it assigns this
|
|
text to the message's *preamble* attribute. When the
|
|
:class:`~email.generator.Generator` is writing out the plain text
|
|
representation of a MIME message, and it finds the
|
|
message has a *preamble* attribute, it will write this text in the area
|
|
between the headers and the first boundary. See :mod:`email.parser` and
|
|
:mod:`email.generator` for details.
|
|
|
|
Note that if the message object has no preamble, the *preamble* attribute
|
|
will be ``None``.
|
|
|
|
|
|
.. attribute:: epilogue
|
|
|
|
The *epilogue* attribute acts the same way as the *preamble* attribute,
|
|
except that it contains text that appears between the last boundary and
|
|
the end of the message.
|
|
|
|
You do not need to set the epilogue to the empty string in order for the
|
|
:class:`Generator` to print a newline at the end of the file.
|
|
|
|
|
|
.. attribute:: defects
|
|
|
|
The *defects* attribute contains a list of all the problems found when
|
|
parsing this message. See :mod:`email.errors` for a detailed description
|
|
of the possible parsing defects.
|