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The "SameSite" attribute defined in RFC 6265bis [1] allows the "Strict", "Lax" and "None" enforcement modes. We already documented "Strict" and "Lax" as being valid values but "None" was missing from the list. While the RFC has not been formally approved, modern browsers support the "None" value [2, 3] thereby making sense to document it. [1]: https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-rfc6265bis [2]: https://developers.google.com/search/blog/2020/01/get-ready-for-new-samesitenone-secure [3]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Set-Cookie#none --------- Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
316 lines
9.9 KiB
ReStructuredText
316 lines
9.9 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 didn't follow the character rules outlined in those specs; many
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current-day browsers and servers have also relaxed parsing rules when it comes
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to cookie handling. As a result, this module now uses parsing rules that are a
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bit less strict than they once were.
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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 a 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:`~BaseCookie.value_decode`
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and :meth:`~BaseCookie.value_encode`. :class:`!SimpleCookie` supports
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strings as cookie values. When setting the value, :class:`!SimpleCookie`
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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:`~Morsel.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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.. attribute:: 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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partitioned
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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` controls when the browser sends the cookie with
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cross-site requests. This helps to mitigate CSRF attacks. Valid values are
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"Strict" (only sent with same-site requests), "Lax" (sent with same-site
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requests and top-level navigations), and "None" (sent with same-site and
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cross-site requests). When using "None", the "secure" attribute must also
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be set, as required by modern browsers.
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The attribute :attr:`partitioned` indicates to user agents that these
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cross-site cookies *should* only be available in the same top-level context
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that the cookie was first set in. For this to be accepted by the user agent,
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you **must** also set ``Secure``.
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In addition, it is recommended to use the ``__Host`` prefix when setting
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partitioned cookies to make them bound to the hostname and not the
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registrable domain. Read
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`CHIPS (Cookies Having Independent Partitioned State)`_
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for full details and examples.
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.. _CHIPS (Cookies Having Independent Partitioned State): https://github.com/privacycg/CHIPS/blob/main/README.md
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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:`!__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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.. versionchanged:: 3.14
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Added support for the :attr:`partitioned` 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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