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lnkohana/system/guide/kohana/cookies.md
2013-04-22 14:09:50 +10:00

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# Cookies
Kohana provides classes that make it easy to work with both cookies and sessions. At a high level both sessions and cookies provide the same functionality. They allow the developer to store temporary or persistent information about a specific client for later retrieval, usually to make something persistent between requests.
[Cookies](http://en.wikipedia.org/wiki/HTTP_cookie) should be used for storing non-private data that is persistent for a long period of time. For example storing a user preference or a language setting. Use the [Cookie] class for getting and setting cookies.
[!!] Kohana uses "signed" cookies. Every cookie that is stored is combined with a secure hash to prevent modification of the cookie. If a cookie is modified outside of Kohana the hash will be incorrect and the cookie will be deleted. This hash is generated using [Cookie::salt()], which uses the [Cookie::$salt] property. You must define this setting in your bootstrap.php:
Cookie::$salt = 'foobar';
Or define an extended cookie class in your application:
class Cookie extends Kohana_Cookie
{
public static $salt = 'foobar';
}
You should set the salt to a secure value. The example above is only for demonstrative purposes.
Nothing stops you from using `$_COOKIE` like normal, but you can not mix using the Cookie class and the regular `$_COOKIE` global, because the hash that Kohana uses to sign cookies will not be present, and Kohana will delete the cookie.
## Storing, Retrieving, and Deleting Data
[Cookie] and [Session] provide a very similar API for storing data. The main difference between them is that sessions are accessed using an object, and cookies are accessed using a static class.
### Storing Data
Storing session or cookie data is done using the [Cookie::set] method:
// Set cookie data
Cookie::set($key, $value);
// Store a user id
Cookie::set('user_id', 10);
### Retrieving Data
Getting session or cookie data is done using the [Cookie::get] method:
// Get cookie data
$data = Cookie::get($key, $default_value);
// Get the user id
$user = Cookie::get('user_id');
### Deleting Data
Deleting session or cookie data is done using the [Cookie::delete] method:
// Delete cookie data
Cookie::delete($key);
// Delete the user id
Cookie::delete('user_id');
## Cookie Settings
All of the cookie settings are changed using static properties. You can either change these settings in `bootstrap.php` or by using [transparent extension](extension). Always check these settings before making your application live, as many of them will have a direct affect on the security of your application.
The most important setting is [Cookie::$salt], which is used for secure signing. This value should be changed and kept secret:
Cookie::$salt = 'your secret is safe with me';
[!!] Changing this value will render all cookies that have been set before invalid.
By default, cookies are stored until the browser is closed. To use a specific lifetime, change the [Cookie::$expiration] setting:
// Set cookies to expire after 1 week
Cookie::$expiration = 604800;
// Alternative to using raw integers, for better clarity
Cookie::$expiration = Date::WEEK;
The path that the cookie can be accessed from can be restricted using the [Cookie::$path] setting.
// Allow cookies only when going to /public/*
Cookie::$path = '/public/';
The domain that the cookie can be accessed from can also be restricted, using the [Cookie::$domain] setting.
// Allow cookies only on the domain www.example.com
Cookie::$domain = 'www.example.com';
If you want to make the cookie accessible on all subdomains, use a dot at the beginning of the domain.
// Allow cookies to be accessed on example.com and *.example.com
Cookie::$domain = '.example.com';
To only allow the cookie to be accessed over a secure (HTTPS) connection, use the [Cookie::$secure] setting.
// Allow cookies to be accessed only on a secure connection
Cookie::$secure = TRUE;
// Allow cookies to be accessed on any connection
Cookie::$secure = FALSE;
To prevent cookies from being accessed using Javascript, you can change the [Cookie::$httponly] setting.
// Make cookies inaccessible to Javascript
Cookie::$httponly = TRUE;