http.cookies — HTTP Cookies

Purpose:Defines classes for parsing and creating HTTP cookie headers.

The http.cookies module implements a parser for cookies that is mostly RFC 2109 compliant. The implementation is a little less strict than the standard because MSIE 3.0x does not support the entire standard.

Morsels

It is also possible to control the other aspects of a cookie, such as the expiration, path, and domain. In fact, all of the RFC attributes for cookies can be managed through the Morsel object representing the cookie value.

http_cookies_Morsel.py
from http import cookies
import datetime


def show_cookie(c):
    print(c)
    for key, morsel in c.items():
        print()
        print('key =', morsel.key)
        print('  value =', morsel.value)
        print('  coded_value =', morsel.coded_value)
        for name in morsel.keys():
            if morsel[name]:
                print('  {} = {}'.format(name, morsel[name]))

c = cookies.SimpleCookie()

# A cookie with a value that has to be encoded
# to fit into the header
c['encoded_value_cookie'] = '"cookie,value;"'
c['encoded_value_cookie']['comment'] = 'Has escaped punctuation'

# A cookie that only applies to part of a site
c['restricted_cookie'] = 'cookie_value'
c['restricted_cookie']['path'] = '/sub/path'
c['restricted_cookie']['domain'] = 'PyMOTW'
c['restricted_cookie']['secure'] = True

# A cookie that expires in 5 minutes
c['with_max_age'] = 'expires in 5 minutes'
c['with_max_age']['max-age'] = 300  # seconds

# A cookie that expires at a specific time
c['expires_at_time'] = 'cookie_value'
time_to_live = datetime.timedelta(hours=1)
expires = (datetime.datetime(2009, 2, 14, 18, 30, 14) +
           time_to_live)

# Date format: Wdy, DD-Mon-YY HH:MM:SS GMT
expires_at_time = expires.strftime('%a, %d %b %Y %H:%M:%S')
c['expires_at_time']['expires'] = expires_at_time

show_cookie(c)

This example includes two different methods for setting stored cookies that expire. One sets the max-age to a number of seconds, the other sets expires to a date and time when the cookie should be discarded.

$ python3 http_cookies_Morsel.py

Set-Cookie: encoded_value_cookie="\"cookie\054value\073\"";
Comment=Has escaped punctuation
Set-Cookie: expires_at_time=cookie_value; expires=Sat, 14 Feb
2009 19:30:14
Set-Cookie: restricted_cookie=cookie_value; Domain=PyMOTW;
Path=/sub/path; Secure
Set-Cookie: with_max_age="expires in 5 minutes"; Max-Age=300

key = with_max_age
  value = expires in 5 minutes
  coded_value = "expires in 5 minutes"
  max-age = 300

key = expires_at_time
  value = cookie_value
  coded_value = cookie_value
  expires = Sat, 14 Feb 2009 19:30:14

key = restricted_cookie
  value = cookie_value
  coded_value = cookie_value
  domain = PyMOTW
  path = /sub/path
  secure = True

key = encoded_value_cookie
  value = "cookie,value;"
  coded_value = "\"cookie\054value\073\""
  comment = Has escaped punctuation

Both the Cookie and Morsel objects act like dictionaries. A Morsel responds to a fixed set of keys:

  • expires
  • path
  • comment
  • domain
  • max-age
  • secure
  • version

The keys for a Cookie instance are the names of the individual cookies being stored. That information is also available from the key attribute of the Morsel.

Encoded Values

The cookie header needs values to be encoded so they can be parsed properly.

http_cookies_coded_value.py
from http import cookies


c = cookies.SimpleCookie()
c['integer'] = 5
c['with_quotes'] = 'He said, "Hello, World!"'

for name in ['integer', 'with_quotes']:
    print(c[name].key)
    print('  {}'.format(c[name]))
    print('  value={!r}'.format(c[name].value))
    print('  coded_value={!r}'.format(c[name].coded_value))
    print()

Morsel.value is always the decoded value of the cookie, while Morsel.coded_value is always the representation to be used for transmitting the value to the client. Both values are always strings. Values saved to a cookie that are not strings are converted automatically.

$ python3 http_cookies_coded_value.py

integer
  Set-Cookie: integer=5
  value='5'
  coded_value='5'

with_quotes
  Set-Cookie: with_quotes="He said\054 \"Hello\054 World!\""
  value='He said, "Hello, World!"'
  coded_value='"He said\\054 \\"Hello\\054 World!\\""'

Alternative Output Formats

Besides using the Set-Cookie header, servers may deliver JavaScript that adds cookies to a client. SimpleCookie and Morsel provide JavaScript output via the js_output() method.

http_cookies_js_output.py
from http import cookies
import textwrap


c = cookies.SimpleCookie()
c['mycookie'] = 'cookie_value'
c['another_cookie'] = 'second value'
js_text = c.js_output()
print(textwrap.dedent(js_text).lstrip())

The result is a complete script tag with statements to set the cookies.

$ python3 http_cookies_js_output.py

<script type="text/javascript">
<!-- begin hiding
document.cookie = "another_cookie=\"second value\"";
// end hiding -->
</script>

<script type="text/javascript">
<!-- begin hiding
document.cookie = "mycookie=cookie_value";
// end hiding -->
</script>

See also