title: Cookies
summary: A set of static methods for manipulating PHP cookies.

# Cookies
## Accessing and Manipulating Cookies

Cookies are a mechanism for storing data in the remote browser and thus tracking or identifying return users. 

SilverStripe uses cookies for remembering users preferences. Application code can modify a users cookies through
the [Cookie](api:SilverStripe\Control\Cookie) class. This class mostly follows the PHP API.

### set

Sets the value of cookie with configuration.


```php
use SilverStripe\Control\Cookie;

Cookie::set($name, $value, $expiry = 90, $path = null, $domain = null, $secure = false, $httpOnly = false);

// Cookie::set('MyApplicationPreference', 'Yes');
```

### get

Returns the value of cookie.


```php
Cookie::get($name);

// Cookie::get('MyApplicationPreference');
// returns 'Yes'
```

### force_expiry

Clears a given cookie.


```php
Cookie::force_expiry($name, $path = null, $domain = null);

// Cookie::force_expiry('MyApplicationPreference')
```

## Cookie_Backend

The [Cookie](api:SilverStripe\Control\Cookie) class manipulates and sets cookies using a [Cookie_Backend](api:SilverStripe\Control\Cookie_Backend). The backend is in charge of the logic
that fetches, sets and expires cookies. By default we use a [CookieJar](api:SilverStripe\Control\CookieJar) backend which uses PHP's 
[setcookie](http://www.php.net/manual/en/function.setcookie.php) function.

The [CookieJar](api:SilverStripe\Control\CookieJar) keeps track of cookies that have been set by the current process as well as those that were received
from the browser.


```php
use SilverStripe\Core\Injector\Injector;
use SilverStripe\Control\Cookie;
use SilverStripe\Control\CookieJar;

$myCookies = [
    'cookie1' => 'value1',
];

$newBackend = new CookieJar($myCookies);

Injector::inst()->registerService($newBackend, 'Cookie_Backend');

Cookie::get('cookie1');

```

### Resetting the Cookie_Backend state

Assuming that your application hasn't messed around with the `$_COOKIE` superglobal, you can reset the state of your
`Cookie_Backend` by simply unregistering the `CookieJar` service with `Injector`. Next time you access `Cookie` it'll
create a new service for you using the `$_COOKIE` superglobal.


```php
Injector::inst()->unregisterNamedObject('Cookie_Backend');

Cookie::get('cookiename'); // will return $_COOKIE['cookiename'] if set
```

Alternatively, if you know that the superglobal has been changed (or you aren't sure it hasn't) you can attempt to use
the current `CookieJar` service to tell you what it was like when it was registered.


```php
//store the cookies that were loaded into the `CookieJar`
$recievedCookie = Cookie::get_inst()->getAll(false);

//set a new `CookieJar`
Injector::inst()->registerService(new CookieJar($recievedCookie), 'CookieJar');
```

### Using your own Cookie_Backend

If you need to implement your own Cookie_Backend you can use the injector system to force a different class to be used.


```yml
---
Name: mycookie
After: '#cookie'
---
SilverStripe\Core\Injector\Injector:
  Cookie_Backend:
    class: MyCookieJar
```

To be a valid backend your class must implement the [Cookie_Backend](api:SilverStripe\Control\Cookie_Backend) interface.

## Advanced Usage

### Sent vs Received Cookies

Sometimes it's useful to be able to tell if a cookie was set by the process (thus will be sent to the browser) or if it
came from the browser as part of the request.

Using the `Cookie_Backend` we can do this like such:


```php
Cookie::set('CookieName', 'CookieVal');

Cookie::get('CookieName'); //gets the cookie as we set it

//will return the cookie as it was when it was sent in the request
Cookie::get('CookieName', false);
```

### Accessing all the cookies at once

One can also access all of the cookies in one go using the `Cookie_Backend`


```php
Cookie::get_inst()->getAll(); //returns all the cookies including ones set during the current process

Cookie::get_inst()->getAll(false); //returns all the cookies in the request
```

## API Documentation

* [Cookie](api:SilverStripe\Control\Cookie)
* [CookieJar](api:SilverStripe\Control\CookieJar)
* [Cookie_Backend](api:SilverStripe\Control\Cookie_Backend)