20.22. Cookie — HTTP state management
Note
The Cookie module has been renamed to http.cookies in Python 3. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.
Source code: Lib/Cookie.py
The Cookie 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, string.ascii_letters, string.digits and !#$%&'*+-.^_`|~ denote the set of valid characters allowed by this module in Cookie name (as key).
Note
On encountering an invalid cookie, CookieError is raised, so if your cookie data comes from a browser you should always prepare for invalid data and catch CookieError on parsing.
-
exception
Cookie.CookieError -
Exception failing because of RFC 2109 invalidity: incorrect attributes, incorrect Set-Cookie header, etc.
-
class
Cookie.BaseCookie( [ input ] ) -
This class is a dictionary-like object whose keys are strings and whose values are
Morselinstances. Note that upon setting a key to a value, the value is first converted to aMorselcontaining the key and the value.If input is given, it is passed to the
load()method.
-
class
Cookie.SimpleCookie( [ input ] ) -
This class derives from
BaseCookieand overridesvalue_decode()andvalue_encode()to be the identity andstr()respectively.
-
class
Cookie.SerialCookie( [ input ] ) -
This class derives from
BaseCookieand overridesvalue_decode()andvalue_encode()to be thepickle.loads()andpickle.dumps().Deprecated since version 2.3: Reading pickled values from untrusted cookie data is a huge security hole, as pickle strings can be crafted to cause arbitrary code to execute on your server. It is supported for backwards compatibility only, and may eventually go away.
-
class
Cookie.SmartCookie( [ input ] ) -
This class derives from
BaseCookie. It overridesvalue_decode()to bepickle.loads()if it is a valid pickle, and otherwise the value itself. It overridesvalue_encode()to bepickle.dumps()unless it is a string, in which case it returns the value itself.Deprecated since version 2.3: The same security warning from
SerialCookieapplies here.
A further security note is warranted. For backwards compatibility, the Cookie module exports a class named Cookie which is just an alias for SmartCookie. This is probably a mistake and will likely be removed in a future version. You should not use the Cookie class in your applications, for the same reason why you should not use the SerialCookie class.
See also
20.22.1. Cookie Objects
-
BaseCookie.value_decode( val ) -
Return a decoded value from a string representation. Return value can be any type. This method does nothing in
BaseCookie— it exists so it can be overridden.
-
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
BaseCookie— it exists so it can be overridden.In general, it should be the case that
value_encode()andvalue_decode()are inverses on the range of value_decode.
-
BaseCookie.output( [ attrs [, header [, sep ] ] ] ) -
Return a string representation suitable to be sent as HTTP headers. attrs and header are sent to each
Morsel’soutput()method. sep is used to join the headers together, and is by default the combination'\r\n'(CRLF).Changed in version 2.5: The default separator has been changed from
'\n'to match the cookie specification.
-
BaseCookie.js_output( [ attrs ] ) -
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
output().
-
BaseCookie.load( rawdata ) -
If rawdata is a string, parse it as an
HTTP_COOKIEand add the values found there asMorsels. If it is a dictionary, it is equivalent to:for k, v in rawdata.items(): cookie[k] = v
20.22.2. Morsel Objects
-
class
Cookie.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
expirespathcommentdomainmax-agesecureversionhttponly
The attribute
httponlyspecifies 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 keys are case-insensitive.
New in version 2.6: The
httponlyattribute was added.
-
Morsel.isReservedKey( K ) -
Whether K is a member of the set of keys of a
Morsel.
-
Morsel.output( [ attrs [, header ] ] ) -
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:".
-
Morsel.js_output( [ attrs ] ) -
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
output().
-
Morsel.OutputString( [ attrs ] ) -
Return a string representing the Morsel, without any surrounding HTTP or JavaScript.
The meaning for attrs is the same as in
output().
20.22.3. Example
The following example demonstrates how to use the Cookie module.
>>> import Cookie
>>> C = Cookie.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 = Cookie.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 = Cookie.SimpleCookie()
>>> C.load("chips=ahoy; vienna=finger") # load from a string (HTTP header)
>>> print C
Set-Cookie: chips=ahoy
Set-Cookie: vienna=finger
>>> C = Cookie.SimpleCookie()
>>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";')
>>> print C
Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;"
>>> C = Cookie.SimpleCookie()
>>> C["oreo"] = "doublestuff"
>>> C["oreo"]["path"] = "/"
>>> print C
Set-Cookie: oreo=doublestuff; Path=/
>>> C["twix"] = "none for you"
>>> C["twix"].value
'none for you'
>>> C = Cookie.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
>>> # SerialCookie and SmartCookie are deprecated
>>> # using it can cause security loopholes in your code.
>>> C = Cookie.SerialCookie()
>>> C["number"] = 7
>>> C["string"] = "seven"
>>> C["number"].value
7
>>> C["string"].value
'seven'
>>> print C
Set-Cookie: number="I7\012."
Set-Cookie: string="S'seven'\012p1\012."
>>> C = Cookie.SmartCookie()
>>> C["number"] = 7
>>> C["string"] = "seven"
>>> C["number"].value
7
>>> C["string"].value
'seven'
>>> print C
Set-Cookie: number="I7\012."
Set-Cookie: string=seven
