20.22. Cookie — HTTP state management — Python v2.7.5 documentation

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# 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 `Morsel` instances. Note that upon setting a key to a value, the value is first converted to a `Morsel` containing the key and the value.

  If input is given, it is passed to the `load()` method.

class `Cookie.` `SimpleCookie`([input])

  This class derives from `BaseCookie` and overrides `value_decode()` and `value_encode()` to be the identity and `str()` respectively.

class `Cookie.` `SerialCookie`([input])

  This class derives from `BaseCookie` and overrides `value_decode()` and `value_encode()` to be the `pickle.loads()` and `pickle.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 overrides `value_decode()` to be `pickle.loads()` if it is a valid pickle, and otherwise the value itself. It overrides `value_encode()` to be `pickle.dumps()` unless it is a string, in which case it returns the value itself.

  Deprecated since version 2.3: The same security warning from `SerialCookie` applies 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

Module `cookielib`
  HTTP cookie handling for web clients. The `cookielib` and `Cookie` modules do not depend on each other.
RFC 2109 - HTTP State Management Mechanism
  This is the state management specification implemented by this module.

## 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()` and `value_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`‘s `output()` 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_COOKIE` and add the values found there as `Morsel`s. 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

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

  The attribute `httponly` specifies that the cookie is only transfered 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 `httponly` attribute was added.

`Morsel.` `value`

  The value of the cookie.

`Morsel.` `coded_value`

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

`Morsel.` `key`

  The name of the cookie.

`Morsel.` `set`(key, value, coded_value)

  Set the key, value and coded_value attributes.

`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

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