:mod:`email.contentmanager`: Managing MIME Content
--------------------------------------------------
.. module:: email.contentmanager
:synopsis: Storing and Retrieving Content from MIME Parts
.. moduleauthor:: R. David Murray <rdmurray@bitdance.com>
.. sectionauthor:: R. David Murray <rdmurray@bitdance.com>
**Source code:** :source:`Lib/email/contentmanager.py`
------------
.. versionadded:: 3.6 [1]_
.. class:: ContentManager()
Base class for content managers. Provides the standard registry mechanisms
to register converters between MIME content and other representations, as
well as the ``get_content`` and ``set_content`` dispatch methods.
.. method:: get_content(msg, *args, **kw)
Look up a handler function based on the ``mimetype`` of *msg* (see next
paragraph), call it, passing through all arguments, and return the result
of the call. The expectation is that the handler will extract the
payload from *msg* and return an object that encodes information about
the extracted data.
To find the handler, look for the following keys in the registry,
stopping with the first one found:
* the string representing the full MIME type (``maintype/subtype``)
* the string representing the ``maintype``
* the empty string
If none of these keys produce a handler, raise a :exc:`KeyError` for the
full MIME type.
.. method:: set_content(msg, obj, *args, **kw)
If the ``maintype`` is ``multipart``, raise a :exc:`TypeError`; otherwise
look up a handler function based on the type of *obj* (see next
paragraph), call :meth:`~email.message.EmailMessage.clear_content` on the
*msg*, and call the handler function, passing through all arguments. The
expectation is that the handler will transform and store *obj* into
*msg*, possibly making other changes to *msg* as well, such as adding
various MIME headers to encode information needed to interpret the stored
data.
To find the handler, obtain the type of *obj* (``typ = type(obj)``), and
look for the following keys in the registry, stopping with the first one
found:
* the type itself (``typ``)
* the type's fully qualified name (``typ.__module__ + '.' +
typ.__qualname__``).
* the type's qualname (``typ.__qualname__``)
* the type's name (``typ.__name__``).
If none of the above match, repeat all of the checks above for each of
the types in the :term:`MRO` (``typ.__mro__``). Finally, if no other key
yields a handler, check for a handler for the key ``None``. If there is
no handler for ``None``, raise a :exc:`KeyError` for the fully
qualified name of the type.
Also add a :mailheader:`MIME-Version` header if one is not present (see
also :class:`.MIMEPart`).
.. method:: add_get_handler(key, handler)
Record the function *handler* as the handler for *key*. For the possible
values of *key*, see :meth:`get_content`.
.. method:: add_set_handler(typekey, handler)
Record *handler* as the function to call when an object of a type
matching *typekey* is passed to :meth:`set_content`. For the possible
values of *typekey*, see :meth:`set_content`.
Content Manager Instances
~~~~~~~~~~~~~~~~~~~~~~~~~
Currently the email package provides only one concrete content manager,
:data:`raw_data_manager`, although more may be added in the future.
:data:`raw_data_manager` is the
:attr:`~email.policy.EmailPolicy.content_manager` provided by
:attr:`~email.policy.EmailPolicy` and its derivatives.
.. data:: raw_data_manager
This content manager provides only a minimum interface beyond that provided
by :class:`~email.message.Message` itself: it deals only with text, raw
byte strings, and :class:`~email.message.Message` objects. Nevertheless, it
provides significant advantages compared to the base API: ``get_content`` on
a text part will return a unicode string without the application needing to
manually decode it, ``set_content`` provides a rich set of options for
controlling the headers added to a part and controlling the content transfer
encoding, and it enables the use of the various ``add_`` methods, thereby
simplifying the creation of multipart messages.
.. method:: get_content(msg, errors='replace')
Return the payload of the part as either a string (for ``text`` parts), an
:class:`~email.message.EmailMessage` object (for ``message/rfc822``
parts), or a ``bytes`` object (for all other non-multipart types). Raise
a :exc:`KeyError` if called on a ``multipart``. If the part is a
``text`` part and *errors* is specified, use it as the error handler when
decoding the payload to unicode. The default error handler is
``replace``.
.. method:: set_content(msg, <'str'>, subtype="plain", charset='utf-8', \
cte=None, \
disposition=None, filename=None, cid=None, \
params=None, headers=None)
set_content(msg, <'bytes'>, maintype, subtype, cte="base64", \
disposition=None, filename=None, cid=None, \
params=None, headers=None)
set_content(msg, <'EmailMessage'>, cte=None, \
disposition=None, filename=None, cid=None, \
params=None, headers=None)
Add headers and payload to *msg*:
Add a :mailheader:`Content-Type` header with a ``maintype/subtype``
value.
* For ``str``, set the MIME ``maintype`` to ``text``, and set the
subtype to *subtype* if it is specified, or ``plain`` if it is not.
* For ``bytes``, use the specified *maintype* and *subtype*, or
raise a :exc:`TypeError` if they are not specified.
* For :class:`~email.message.EmailMessage` objects, set the maintype
to ``message``, and set the subtype to *subtype* if it is
specified or ``rfc822`` if it is not. If *subtype* is
``partial``, raise an error (``bytes`` objects must be used to
construct ``message/partial`` parts).
If *charset* is provided (which is valid only for ``str``), encode the
string to bytes using the specified character set. The default is
``utf-8``. If the specified *charset* is a known alias for a standard
MIME charset name, use the standard charset instead.
If *cte* is set, encode the payload using the specified content transfer
encoding, and set the :mailheader:`Content-Transfer-Encoding` header to
that value. Possible values for *cte* are ``quoted-printable``,
``base64``, ``7bit``, ``8bit``, and ``binary``. If the input cannot be
encoded in the specified encoding (for example, specifying a *cte* of
``7bit`` for an input that contains non-ASCII values), raise a
:exc:`ValueError`.
* For ``str`` objects, if *cte* is not set use heuristics to
determine the most compact encoding.
* For :class:`~email.message.EmailMessage`, per :rfc:`2046`, raise
an error if a *cte* of ``quoted-printable`` or ``base64`` is
requested for *subtype* ``rfc822``, and for any *cte* other than
``7bit`` for *subtype* ``external-body``. For
``message/rfc822``, use ``8bit`` if *cte* is not specified. For
all other values of *subtype*, use ``7bit``.
.. note:: A *cte* of ``binary`` does not actually work correctly yet.
The ``EmailMessage`` object as modified by ``set_content`` is
correct, but :class:`~email.generator.BytesGenerator` does not
serialize it correctly.
If *disposition* is set, use it as the value of the
:mailheader:`Content-Disposition` header. If not specified, and
*filename* is specified, add the header with the value ``attachment``.
If *disposition* is not specified and *filename* is also not specified,
do not add the header. The only valid values for *disposition* are
``attachment`` and ``inline``.
If *filename* is specified, use it as the value of the ``filename``
parameter of the :mailheader:`Content-Disposition` header.
If *cid* is specified, add a :mailheader:`Content-ID` header with
*cid* as its value.
If *params* is specified, iterate its ``items`` method and use the
resulting ``(key, value)`` pairs to set additional parameters on the
:mailheader:`Content-Type` header.
If *headers* is specified and is a list of strings of the form
``headername: headervalue`` or a list of ``header`` objects
(distinguished from strings by having a ``name`` attribute), add the
headers to *msg*.
.. rubric:: Footnotes
.. [1] Originally added in 3.4 as a :term:`provisional module <provisional
package>`
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