6.2. Cookie operations

The standard Python Cookie module has the operations you will need to handle cookies. Import it like this:

import Cookie

To create a new cookie c from a string s:

    c = Cookie.SimpleCookie ( s )

Internally, a cookie is a set of key-value pairs. Most applications use only one name and one value, but it is possible to have several. Each key-value pair is kept in an instance of class Morsel.

Here are the operations on an instance C of class SimpleCookie.

C.has_key ( key ): Returns True if C has a key that matches key; otherwise, it returns False.
C[key]: Return the Morsel instance for the given key, if there is one, otherwise raise KeyError.
C[key] = s: Add a new Morsel to C with the given key and some string value s.
print C.output(): Do this to set C as the current cookie, before you have sent any other headers such as the Content-type header.

Here are the operations on a Morsel instances M.

M.key: The key for this morsel.
M.value: The value for this morsel.

Instances of Morsel also act like dictionaries, except that only certain keys are allowed. You may read or set entries in this dictionary. Allowable keys include:

'max-age'

The cookie's maximum age in seconds. If you would like to log the user out of your site after a set period of time, you can use this attribute to determine when their cookie will expire.

You can set this value to a large interval, such as five years, to create what is called a persistent cookie. Such a cookie will live on even when the user kills and restarts their browser.

Setting this value to zero ('0') causes the cookie to be deleted.

'path'

Use this value to limit this cookie to only a certain directory on your site. It Specifies the URL of the top directory of your site, relative to the server. For example, if your site's pages are all at or below the URL http://www.nmt.edu/~pat/cgi/, the relative path would be '/~pat/cgi/'.

If you specify this attribute, users who come to your server but not inside your site will not see your cookies.

'secure'

Set this attribute to any value to request that cookies be carried only through secure channels such as the https: protocol. Disclaimer: This is not a complete security mechanism. Seek expert help if you are handling sensitive data.

'comment'

You may set a value for this attribute as a comment to explain what the cookie is for. Users can ask their browser to show them this comment while they are deciding whether or not to accept your cookie.

Dynamic Web content and forms processing in Python

6.2. Cookie operations