Using Cookies in TurboGears

Setting a Cookie

To set a cookie, you'll need to make sure cherrypy is imported and set a few options. Here's an example:

import cherrypy

cherrypy.response.simple_cookie['user_name'] = 'TurboGears User'

Here we've set up a cookie called user_name that has the value "TurboGears User". It doesn't matter if you create a new cookie or if you overwrite an existing one, just assign the value to a key with the name of your cookie.

The simple_cookie object basically behaves like a Python dictionary and all cookies you set will be sent automatically to the client. You can read more about further options for cookies in the Python Cookie Module Documentation.

Reading a Cookie

To read a cookie, we use the cherrypy.request.simple_cookie object. Let's say we want to find the value for the user_name cookie:

username = cherrypy.request.simple_cookie['user_name'].value

If you don't know, whether a cookie is set, you can test it using normal Python dictionary methods:

if cherrypy.request.simple_cookie.has_key('user_name'):
    # do something

or better just:

try:
    username = cherrypy.request.simple_cookie['user_name'].value
except KeyError:
    # do something else

It's as simple as that!

Deleting a Cookie

Deleting cookies is not quite as straightforward as it would seem, but is nonetheless very easy. All you have to do is set the cookie's expiration to 0. Let's delete the user_name cookie:

cherrypy.response.simple_cookie['user_name']['expires'] = 0

Accessing Cookies in Templates

If you want to read or write cookies in your templates (though doing so might be considered a violation of of the MVC pattern), you can add the simple_cookie object as a custom template variable:

from turbogears.view import variable_providers

def add_cookie(vars):
    vars['cookie'] = cherrypy.response.simple_cookie

variable_providers.append(add_cookie)

Now the simple_cookie object will be available as tg.cookie in all your templates. The page Global Template Variables has more about custom template variables in the section "Custom Additions".