295 lines
8.8 KiB
ReStructuredText
295 lines
8.8 KiB
ReStructuredText
:mod:`http.cookies` --- HTTP state management
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=============================================
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.. module:: http.cookies
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:synopsis: Support for HTTP state management (cookies).
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.. moduleauthor:: Timothy O'Malley <timo@alum.mit.edu>
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.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
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**Source code:** :source:`Lib/http/cookies.py`
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--------------
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The :mod:`http.cookies` module defines classes for abstracting the concept of
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cookies, an HTTP state management mechanism. It supports both simple string-only
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cookies, and provides an abstraction for having any serializable data-type as
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cookie value.
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The module formerly strictly applied the parsing rules described in the
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:rfc:`2109` and :rfc:`2068` specifications. It has since been discovered that
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MSIE 3.0x doesn't follow the character rules outlined in those specs and also
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many current day browsers and servers have relaxed parsing rules when comes to
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Cookie handling. As a result, the parsing rules used are a bit less strict.
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The character set, :data:`string.ascii_letters`, :data:`string.digits` and
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``!#$%&'*+-.^_`|~:`` denote the set of valid characters allowed by this module
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in Cookie name (as :attr:`~Morsel.key`).
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.. versionchanged:: 3.3
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Allowed ':' as a valid Cookie name character.
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.. note::
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On encountering an invalid cookie, :exc:`CookieError` is raised, so if your
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cookie data comes from a browser you should always prepare for invalid data
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and catch :exc:`CookieError` on parsing.
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.. exception:: CookieError
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Exception failing because of :rfc:`2109` invalidity: incorrect attributes,
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incorrect :mailheader:`Set-Cookie` header, etc.
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.. class:: BaseCookie([input])
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This class is a dictionary-like object whose keys are strings and whose values
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are :class:`Morsel` instances. Note that upon setting a key to a value, the
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value is first converted to a :class:`Morsel` containing the key and the value.
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If *input* is given, it is passed to the :meth:`load` method.
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.. class:: SimpleCookie([input])
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This class derives from :class:`BaseCookie` and overrides :meth:`value_decode`
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and :meth:`value_encode`. SimpleCookie supports strings as cookie values.
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When setting the value, SimpleCookie calls the builtin :func:`str()` to convert
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the value to a string. Values received from HTTP are kept as strings.
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.. seealso::
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Module :mod:`http.cookiejar`
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HTTP cookie handling for web *clients*. The :mod:`http.cookiejar` and
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:mod:`http.cookies` modules do not depend on each other.
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:rfc:`2109` - HTTP State Management Mechanism
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This is the state management specification implemented by this module.
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.. _cookie-objects:
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Cookie Objects
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--------------
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.. method:: BaseCookie.value_decode(val)
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Return a tuple ``(real_value, coded_value)`` from a string representation.
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``real_value`` can be any type. This method does no decoding in
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:class:`BaseCookie` --- it exists so it can be overridden.
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.. method:: BaseCookie.value_encode(val)
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Return a tuple ``(real_value, coded_value)``. *val* can be any type, but
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``coded_value`` will always be converted to a string.
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This method does no encoding in :class:`BaseCookie` --- it exists so it can
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be overridden.
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In general, it should be the case that :meth:`value_encode` and
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:meth:`value_decode` are inverses on the range of *value_decode*.
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.. method:: BaseCookie.output(attrs=None, header='Set-Cookie:', sep='\\r\\n')
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Return a string representation suitable to be sent as HTTP headers. *attrs* and
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*header* are sent to each :class:`Morsel`'s :meth:`output` method. *sep* is used
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to join the headers together, and is by default the combination ``'\r\n'``
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(CRLF).
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.. method:: BaseCookie.js_output(attrs=None)
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Return an embeddable JavaScript snippet, which, if run on a browser which
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supports JavaScript, will act the same as if the HTTP headers was sent.
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The meaning for *attrs* is the same as in :meth:`output`.
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.. method:: BaseCookie.load(rawdata)
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If *rawdata* is a string, parse it as an ``HTTP_COOKIE`` and add the values
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found there as :class:`Morsel`\ s. If it is a dictionary, it is equivalent to::
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for k, v in rawdata.items():
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cookie[k] = v
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.. _morsel-objects:
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Morsel Objects
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--------------
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.. class:: Morsel
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Abstract a key/value pair, which has some :rfc:`2109` attributes.
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Morsels are dictionary-like objects, whose set of keys is constant --- the valid
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:rfc:`2109` attributes, which are
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* ``expires``
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* ``path``
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* ``comment``
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* ``domain``
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* ``max-age``
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* ``secure``
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* ``version``
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* ``httponly``
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* ``samesite``
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The attribute :attr:`httponly` specifies that the cookie is only transferred
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in HTTP requests, and is not accessible through JavaScript. This is intended
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to mitigate some forms of cross-site scripting.
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The attribute :attr:`samesite` specifies that the browser is not allowed to
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send the cookie along with cross-site requests. This helps to mitigate CSRF
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attacks. Valid values for this attribute are "Strict" and "Lax".
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The keys are case-insensitive and their default value is ``''``.
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.. versionchanged:: 3.5
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:meth:`~Morsel.__eq__` now takes :attr:`~Morsel.key` and :attr:`~Morsel.value`
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into account.
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.. versionchanged:: 3.7
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Attributes :attr:`~Morsel.key`, :attr:`~Morsel.value` and
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:attr:`~Morsel.coded_value` are read-only. Use :meth:`~Morsel.set` for
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setting them.
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.. versionchanged:: 3.8
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Added support for the :attr:`samesite` attribute.
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.. attribute:: Morsel.value
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The value of the cookie.
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.. attribute:: Morsel.coded_value
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The encoded value of the cookie --- this is what should be sent.
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.. attribute:: Morsel.key
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The name of the cookie.
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.. method:: Morsel.set(key, value, coded_value)
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Set the *key*, *value* and *coded_value* attributes.
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.. method:: Morsel.isReservedKey(K)
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Whether *K* is a member of the set of keys of a :class:`Morsel`.
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.. method:: Morsel.output(attrs=None, header='Set-Cookie:')
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Return a string representation of the Morsel, suitable to be sent as an HTTP
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header. By default, all the attributes are included, unless *attrs* is given, in
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which case it should be a list of attributes to use. *header* is by default
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``"Set-Cookie:"``.
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.. method:: Morsel.js_output(attrs=None)
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Return an embeddable JavaScript snippet, which, if run on a browser which
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supports JavaScript, will act the same as if the HTTP header was sent.
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The meaning for *attrs* is the same as in :meth:`output`.
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.. method:: Morsel.OutputString(attrs=None)
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Return a string representing the Morsel, without any surrounding HTTP or
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JavaScript.
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The meaning for *attrs* is the same as in :meth:`output`.
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.. method:: Morsel.update(values)
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Update the values in the Morsel dictionary with the values in the dictionary
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*values*. Raise an error if any of the keys in the *values* dict is not a
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valid :rfc:`2109` attribute.
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.. versionchanged:: 3.5
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an error is raised for invalid keys.
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.. method:: Morsel.copy(value)
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Return a shallow copy of the Morsel object.
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.. versionchanged:: 3.5
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return a Morsel object instead of a dict.
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.. method:: Morsel.setdefault(key, value=None)
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Raise an error if key is not a valid :rfc:`2109` attribute, otherwise
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behave the same as :meth:`dict.setdefault`.
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.. _cookie-example:
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Example
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-------
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The following example demonstrates how to use the :mod:`http.cookies` module.
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.. doctest::
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:options: +NORMALIZE_WHITESPACE
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>>> from http import cookies
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>>> C = cookies.SimpleCookie()
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>>> C["fig"] = "newton"
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>>> C["sugar"] = "wafer"
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>>> print(C) # generate HTTP headers
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Set-Cookie: fig=newton
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Set-Cookie: sugar=wafer
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>>> print(C.output()) # same thing
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Set-Cookie: fig=newton
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Set-Cookie: sugar=wafer
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>>> C = cookies.SimpleCookie()
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>>> C["rocky"] = "road"
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>>> C["rocky"]["path"] = "/cookie"
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>>> print(C.output(header="Cookie:"))
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Cookie: rocky=road; Path=/cookie
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>>> print(C.output(attrs=[], header="Cookie:"))
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Cookie: rocky=road
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>>> C = cookies.SimpleCookie()
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>>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
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>>> print(C)
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Set-Cookie: chips=ahoy
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Set-Cookie: vienna=finger
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>>> C = cookies.SimpleCookie()
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>>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
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>>> print(C)
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Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"
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>>> C = cookies.SimpleCookie()
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>>> C["oreo"] = "doublestuff"
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>>> C["oreo"]["path"] = "/"
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>>> print(C)
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Set-Cookie: oreo=doublestuff; Path=/
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>>> C = cookies.SimpleCookie()
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>>> C["twix"] = "none for you"
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>>> C["twix"].value
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'none for you'
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>>> C = cookies.SimpleCookie()
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>>> C["number"] = 7 # equivalent to C["number"] = str(7)
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>>> C["string"] = "seven"
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>>> C["number"].value
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'7'
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>>> C["string"].value
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'seven'
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>>> print(C)
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Set-Cookie: number=7
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Set-Cookie: string=seven
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