Doc/library/http.cookies.rst

:mod:`http.cookies` --- HTTP state management
=============================================

.. module:: http.cookies
   :synopsis: Support for HTTP state management (cookies).

.. moduleauthor:: Timothy O'Malley <timo@alum.mit.edu>
.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>

**Source code:** :source:`Lib/http/cookies.py`

--------------

The :mod:`http.cookies` module defines classes for abstracting the concept of
cookies, an HTTP state management mechanism. It supports both simple string-only
cookies, and provides an abstraction for having any serializable data-type as
cookie value.

The module formerly strictly applied the parsing rules described in the
:rfc:`2109` and :rfc:`2068` specifications.  It has since been discovered that
MSIE 3.0x doesn't follow the character rules outlined in those specs and also
many current day browsers and servers have relaxed parsing rules when comes to
Cookie handling.  As a result, the parsing rules used are a bit less strict.

The character set, :data:`string.ascii_letters`, :data:`string.digits` and
``!#$%&'*+-.^_`|~:`` denote the set of valid characters allowed by this module
in Cookie name (as :attr:`~Morsel.key`).

.. versionchanged:: 3.3
   Allowed ':' as a valid Cookie name character.


.. note::

   On encountering an invalid cookie, :exc:`CookieError` is raised, so if your
   cookie data comes from a browser you should always prepare for invalid data
   and catch :exc:`CookieError` on parsing.


.. exception:: CookieError

   Exception failing because of :rfc:`2109` invalidity: incorrect attributes,
   incorrect :mailheader:`Set-Cookie` header, etc.


.. class:: BaseCookie([input])

   This class is a dictionary-like object whose keys are strings and whose values
   are :class:`Morsel` instances. Note that upon setting a key to a value, the
   value is first converted to a :class:`Morsel` containing the key and the value.

   If *input* is given, it is passed to the :meth:`load` method.


.. class:: SimpleCookie([input])

   This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`
   and :meth:`value_encode` to be the identity and :func:`str` respectively.


.. seealso::

   Module :mod:`http.cookiejar`
      HTTP cookie handling for web *clients*.  The :mod:`http.cookiejar` and
      :mod:`http.cookies` modules do not depend on each other.

   :rfc:`2109` - HTTP State Management Mechanism
      This is the state management specification implemented by this module.


.. _cookie-objects:

Cookie Objects
--------------


.. method:: BaseCookie.value_decode(val)

   Return a decoded value from a string representation. Return value can be any
   type. This method does nothing in :class:`BaseCookie` --- it exists so it can be
   overridden.


.. method:: BaseCookie.value_encode(val)

   Return an encoded value. *val* can be any type, but return value must be a
   string. This method does nothing in :class:`BaseCookie` --- it exists so it can
   be overridden.

   In general, it should be the case that :meth:`value_encode` and
   :meth:`value_decode` are inverses on the range of *value_decode*.


.. method:: BaseCookie.output(attrs=None, header='Set-Cookie:', sep='\\r\\n')

   Return a string representation suitable to be sent as HTTP headers. *attrs* and
   *header* are sent to each :class:`Morsel`'s :meth:`output` method. *sep* is used
   to join the headers together, and is by default the combination ``'\r\n'``
   (CRLF).


.. method:: BaseCookie.js_output(attrs=None)

   Return an embeddable JavaScript snippet, which, if run on a browser which
   supports JavaScript, will act the same as if the HTTP headers was sent.

   The meaning for *attrs* is the same as in :meth:`output`.


.. method:: BaseCookie.load(rawdata)

   If *rawdata* is a string, parse it as an ``HTTP_COOKIE`` and add the values
   found there as :class:`Morsel`\ s. If it is a dictionary, it is equivalent to::

      for k, v in rawdata.items():
          cookie[k] = v


.. _morsel-objects:

Morsel Objects
--------------


.. class:: Morsel

   Abstract a key/value pair, which has some :rfc:`2109` attributes.

   Morsels are dictionary-like objects, whose set of keys is constant --- the valid
   :rfc:`2109` attributes, which are

   * ``expires``
   * ``path``
   * ``comment``
   * ``domain``
   * ``max-age``
   * ``secure``
   * ``version``
   * ``httponly``
   * ``samesite``

   The attribute :attr:`httponly` specifies that the cookie is only transferred
   in HTTP requests, and is not accessible through JavaScript. This is intended
   to mitigate some forms of cross-site scripting.

   The attribute :attr:`samesite` specifies that the browser is not allowed to
   send the cookie along with cross-site requests. This helps to mitigate CSRF
   attacks. Valid values for this attribute are "Strict" and "Lax".

   The keys are case-insensitive and their default value is ``''``.

   .. versionchanged:: 3.5
      :meth:`~Morsel.__eq__` now takes :attr:`~Morsel.key` and :attr:`~Morsel.value`
      into account.

   .. versionchanged:: 3.7
      Attributes :attr:`~Morsel.key`, :attr:`~Morsel.value` and
      :attr:`~Morsel.coded_value` are read-only.  Use :meth:`~Morsel.set` for
      setting them.

   .. versionchanged:: 3.8
      Added support for the :attr:`samesite` attribute.


.. attribute:: Morsel.value

   The value of the cookie.


.. attribute:: Morsel.coded_value

   The encoded value of the cookie --- this is what should be sent.


.. attribute:: Morsel.key

   The name of the cookie.


.. method:: Morsel.set(key, value, coded_value)

   Set the *key*, *value* and *coded_value* attributes.


.. method:: Morsel.isReservedKey(K)

   Whether *K* is a member of the set of keys of a :class:`Morsel`.


.. method:: Morsel.output(attrs=None, header='Set-Cookie:')

   Return a string representation of the Morsel, suitable to be sent as an HTTP
   header. By default, all the attributes are included, unless *attrs* is given, in
   which case it should be a list of attributes to use. *header* is by default
   ``"Set-Cookie:"``.


.. method:: Morsel.js_output(attrs=None)

   Return an embeddable JavaScript snippet, which, if run on a browser which
   supports JavaScript, will act the same as if the HTTP header was sent.

   The meaning for *attrs* is the same as in :meth:`output`.


.. method:: Morsel.OutputString(attrs=None)

   Return a string representing the Morsel, without any surrounding HTTP or
   JavaScript.

   The meaning for *attrs* is the same as in :meth:`output`.


.. method:: Morsel.update(values)

   Update the values in the Morsel dictionary with the values in the dictionary
   *values*.  Raise an error if any of the keys in the *values* dict is not a
   valid :rfc:`2109` attribute.

   .. versionchanged:: 3.5
      an error is raised for invalid keys.


.. method:: Morsel.copy(value)

   Return a shallow copy of the Morsel object.

   .. versionchanged:: 3.5
      return a Morsel object instead of a dict.


.. method:: Morsel.setdefault(key, value=None)

   Raise an error if key is not a valid :rfc:`2109` attribute, otherwise
   behave the same as :meth:`dict.setdefault`.


.. _cookie-example:

Example
-------

The following example demonstrates how to use the :mod:`http.cookies` module.

.. doctest::
   :options: +NORMALIZE_WHITESPACE

   >>> from http import cookies
   >>> C = cookies.SimpleCookie()
   >>> C["fig"] = "newton"
   >>> C["sugar"] = "wafer"
   >>> print(C) # generate HTTP headers
   Set-Cookie: fig=newton
   Set-Cookie: sugar=wafer
   >>> print(C.output()) # same thing
   Set-Cookie: fig=newton
   Set-Cookie: sugar=wafer
   >>> C = cookies.SimpleCookie()
   >>> C["rocky"] = "road"
   >>> C["rocky"]["path"] = "/cookie"
   >>> print(C.output(header="Cookie:"))
   Cookie: rocky=road; Path=/cookie
   >>> print(C.output(attrs=[], header="Cookie:"))
   Cookie: rocky=road
   >>> C = cookies.SimpleCookie()
   >>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
   >>> print(C)
   Set-Cookie: chips=ahoy
   Set-Cookie: vienna=finger
   >>> C = cookies.SimpleCookie()
   >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
   >>> print(C)
   Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"
   >>> C = cookies.SimpleCookie()
   >>> C["oreo"] = "doublestuff"
   >>> C["oreo"]["path"] = "/"
   >>> print(C)
   Set-Cookie: oreo=doublestuff; Path=/
   >>> C = cookies.SimpleCookie()
   >>> C["twix"] = "none for you"
   >>> C["twix"].value
   'none for you'
   >>> C = cookies.SimpleCookie()
   >>> C["number"] = 7 # equivalent to C["number"] = str(7)
   >>> C["string"] = "seven"
   >>> C["number"].value
   '7'
   >>> C["string"].value
   'seven'
   >>> print(C)
   Set-Cookie: number=7
   Set-Cookie: string=seven