+ +
+

Session Library

+

The Session class permits you maintain a user’s “state” and track their +activity while they browse your site.

+

CodeIgniter comes with a few session storage drivers:

+
+
    +
  • files (default; file-system based)
    • +
  • database
    • +
  • redis
    • +
  • memcached
    • +
+
+

In addition, you may create your own, custom session drivers based on other +kinds of storage, while still taking advantage of the features of the +Session class.

+ +
+

Using the Session Class

+
+

Initializing a Session

+

Sessions will typically run globally with each page load, so the Session +class should either be initialized in your controller constructors, or it can be auto-loaded by the system. +For the most part the session class will run unattended in the background, +so simply initializing the class will cause it to read, create, and update +sessions when necessary.

+

To initialize the Session class manually in your controller constructor, +use the $this->load->library() method:

+
$this->load->library('session');
+
+
+

Once loaded, the Sessions library object will be available using:

+
$this->session
+
+
+
+

Important

+

Because the Loader Class is instantiated +by CodeIgniter’s base controller, make sure to call +parent::__construct() before trying to load a library from +inside a controller constructor.

+
+
+
+

How do Sessions work?

+

When a page is loaded, the session class will check to see if valid +session cookie is sent by the user’s browser. If a sessions cookie does +not exist (or if it doesn’t match one stored on the server or has +expired) a new session will be created and saved.

+

If a valid session does exist, its information will be updated. With each +update, the session ID may be regenerated if configured to do so.

+

It’s important for you to understand that once initialized, the Session +class runs automatically. There is nothing you need to do to cause the +above behavior to happen. You can, as you’ll see below, work with session +data, but the process of reading, writing, and updating a session is +automatic.

+
+

Note

+

Under CLI, the Session library will automatically halt itself, +as this is a concept based entirely on the HTTP protocol.

+
+
+

A note about concurrency

+

Unless you’re developing a website with heavy AJAX usage, you can skip this +section. If you are, however, and if you’re experiencing performance +issues, then this note is exactly what you’re looking for.

+

Sessions in previous versions of CodeIgniter didn’t implement locking, +which meant that two HTTP requests using the same session could run exactly +at the same time. To use a more appropriate technical term - requests were +non-blocking.

+

However, non-blocking requests in the context of sessions also means +unsafe, because modifications to session data (or session ID regeneration) +in one request can interfere with the execution of a second, concurrent +request. This detail was at the root of many issues and the main reason why +CodeIgniter 3.0 has a completely re-written Session library.

+

Why are we telling you this? Because it is likely that after trying to +find the reason for your performance issues, you may conclude that locking +is the issue and therefore look into how to remove the locks …

+

DO NOT DO THAT! Removing locks would be wrong and it will cause you +more problems!

+

Locking is not the issue, it is a solution. Your issue is that you still +have the session open, while you’ve already processed it and therefore no +longer need it. So, what you need is to close the session for the +current request after you no longer need it.

+

Long story short - call session_write_close() once you no longer need +anything to do with session variables.

+
+
+
+

What is Session Data?

+

Session data is simply an array associated with a particular session ID +(cookie).

+

If you’ve used sessions in PHP before, you should be familiar with PHP’s +$_SESSION superglobal +(if not, please read the content on that link).

+

CodeIgniter gives access to its session data through the same means, as it +uses the session handlers’ mechanism provided by PHP. Using session data is +as simple as manipulating (read, set and unset values) the $_SESSION +array.

+

In addition, CodeIgniter also provides 2 special types of session data +that are further explained below: flashdata and tempdata.

+
+

Note

+

In previous versions, regular session data in CodeIgniter was +referred to as ‘userdata’. Have this in mind if that term is used +elsewhere in the manual. Most of it is written to explain how +the custom ‘userdata’ methods work.

+
+
+
+

Retrieving Session Data

+

Any piece of information from the session array is available through the +$_SESSION superglobal:

+
$_SESSION['item']
+
+
+

Or through the magic getter:

+
$this->session->item
+
+
+

And for backwards compatibility, through the userdata() method:

+
$this->session->userdata('item');
+
+
+

Where item is the array key corresponding to the item you wish to fetch. +For example, to assign a previously stored ‘name’ item to the $name +variable, you will do this:

+
$name = $_SESSION['name'];
+
+// or:
+
+$name = $this->session->name
+
+// or:
+
+$name = $this->session->userdata('name');
+
+
+
+

Note

+

The userdata() method returns NULL if the item you are trying +to access does not exist.

+
+

If you want to retrieve all of the existing userdata, you can simply +omit the item key (magic getter only works for properties):

+
$_SESSION
+
+// or:
+
+$this->session->userdata();
+
+
+
+
+

Adding Session Data

+

Let’s say a particular user logs into your site. Once authenticated, you +could add their username and e-mail address to the session, making that +data globally available to you without having to run a database query when +you need it.

+

You can simply assign data to the $_SESSION array, as with any other +variable. Or as a property of $this->session.

+

Alternatively, the old method of assigning it as “userdata” is also +available. That however passing an array containing your new data to the +set_userdata() method:

+
$this->session->set_userdata($array);
+
+
+

Where $array is an associative array containing your new data. Here’s +an example:

+
$newdata = array(
+        'username'  => 'johndoe',
+        'email'     => 'johndoe@some-site.com',
+        'logged_in' => TRUE
+);
+
+$this->session->set_userdata($newdata);
+
+
+

If you want to add userdata one value at a time, set_userdata() also +supports this syntax:

+
$this->session->set_userdata('some_name', 'some_value');
+
+
+

If you want to verify that a session value exists, simply check with +isset():

+
// returns FALSE if the 'some_name' item doesn't exist or is NULL,
+// TRUE otherwise:
+isset($_SESSION['some_name'])
+
+
+

Or you can call has_userdata():

+
$this->session->has_userdata('some_name');
+
+
+
+
+

Removing Session Data

+

Just as with any other variable, unsetting a value in $_SESSION can be +done through unset():

+
unset($_SESSION['some_name']);
+
+// or multiple values:
+
+unset(
+        $_SESSION['some_name'],
+        $_SESSION['another_name']
+);
+
+
+

Also, just as set_userdata() can be used to add information to a +session, unset_userdata() can be used to remove it, by passing the +session key. For example, if you wanted to remove ‘some_name’ from your +session data array:

+
$this->session->unset_userdata('some_name');
+
+
+

This method also accepts an array of item keys to unset:

+
$array_items = array('username', 'email');
+
+$this->session->unset_userdata($array_items);
+
+
+
+

Note

+

In previous versions, the unset_userdata() method used +to accept an associative array of key => 'dummy value' +pairs. This is no longer supported.

+
+
+
+

Flashdata

+

CodeIgniter supports “flashdata”, or session data that will only be +available for the next request, and is then automatically cleared.

+

This can be very useful, especially for one-time informational, error or +status messages (for example: “Record 2 deleted”).

+

It should be noted that flashdata variables are regular session vars, +only marked in a specific way under the ‘__ci_vars’ key (please don’t touch +that one, you’ve been warned).

+

To mark an existing item as “flashdata”:

+
$this->session->mark_as_flash('item');
+
+
+

If you want to mark multiple items as flashdata, simply pass the keys as an +array:

+
$this->session->mark_as_flash(array('item', 'item2'));
+
+
+

To add flashdata:

+
$_SESSION['item'] = 'value';
+$this->session->mark_as_flash('item');
+
+
+

Or alternatively, using the set_flashdata() method:

+
$this->session->set_flashdata('item', 'value');
+
+
+

You can also pass an array to set_flashdata(), in the same manner as +set_userdata().

+

Reading flashdata variables is the same as reading regular session data +through $_SESSION:

+
$_SESSION['item']
+
+
+
+

Important

+

The userdata() method will NOT return flashdata items.

+
+

However, if you want to be sure that you’re reading “flashdata” (and not +any other kind), you can also use the flashdata() method:

+
$this->session->flashdata('item');
+
+
+

Or to get an array with all flashdata, simply omit the key parameter:

+
$this->session->flashdata();
+
+
+
+

Note

+

The flashdata() method returns NULL if the item cannot be +found.

+
+

If you find that you need to preserve a flashdata variable through an +additional request, you can do so using the keep_flashdata() method. +You can either pass a single item or an array of flashdata items to keep.

+
$this->session->keep_flashdata('item');
+$this->session->keep_flashdata(array('item1', 'item2', 'item3'));
+
+
+
+
+

Tempdata

+

CodeIgniter also supports “tempdata”, or session data with a specific +expiration time. After the value expires, or the session expires or is +deleted, the value is automatically removed.

+

Similarly to flashdata, tempdata variables are regular session vars that +are marked in a specific way under the ‘__ci_vars’ key (again, don’t touch +that one).

+

To mark an existing item as “tempdata”, simply pass its key and expiry time +(in seconds!) to the mark_as_temp() method:

+
// 'item' will be erased after 300 seconds
+$this->session->mark_as_temp('item', 300);
+
+
+

You can mark multiple items as tempdata in two ways, depending on whether +you want them all to have the same expiry time or not:

+
// Both 'item' and 'item2' will expire after 300 seconds
+$this->session->mark_as_temp(array('item', 'item2'), 300);
+
+// 'item' will be erased after 300 seconds, while 'item2'
+// will do so after only 240 seconds
+$this->session->mark_as_temp(array(
+        'item'  => 300,
+        'item2' => 240
+));
+
+
+

To add tempdata:

+
$_SESSION['item'] = 'value';
+$this->session->mark_as_temp('item', 300); // Expire in 5 minutes
+
+
+

Or alternatively, using the set_tempdata() method:

+
$this->session->set_tempdata('item', 'value', 300);
+
+
+

You can also pass an array to set_tempdata():

+
$tempdata = array('newuser' => TRUE, 'message' => 'Thanks for joining!');
+
+$this->session->set_tempdata($tempdata, NULL, $expire);
+
+
+
+

Note

+

If the expiration is omitted or set to 0, the default +time-to-live value of 300 seconds (or 5 minutes) will be used.

+
+

To read a tempdata variable, again you can just access it through the +$_SESSION superglobal array:

+
$_SESSION['item']
+
+
+
+

Important

+

The userdata() method will NOT return tempdata items.

+
+

Or if you want to be sure that you’re reading “tempdata” (and not any +other kind), you can also use the tempdata() method:

+
$this->session->tempdata('item');
+
+
+

And of course, if you want to retrieve all existing tempdata:

+
$this->session->tempdata();
+
+
+
+

Note

+

The tempdata() method returns NULL if the item cannot be +found.

+
+

If you need to remove a tempdata value before it expires, you can directly +unset it from the $_SESSION array:

+
unset($_SESSION['item']);
+
+
+

However, this won’t remove the marker that makes this specific item to be +tempdata (it will be invalidated on the next HTTP request), so if you +intend to reuse that same key in the same request, you’d want to use +unset_tempdata():

+
$this->session->unset_tempdata('item');
+
+
+
+
+

Destroying a Session

+

To clear the current session (for example, during a logout), you may +simply use either PHP’s session_destroy() +function, or the sess_destroy() method. Both will work in exactly the +same way:

+
session_destroy();
+
+// or
+
+$this->session->sess_destroy();
+
+
+
+

Note

+

This must be the last session-related operation that you do +during the same request. All session data (including flashdata and +tempdata) will be destroyed permanently and functions will be +unusable during the same request after you destroy the session.

+
+
+
+

Accessing session metadata

+

In previous CodeIgniter versions, the session data array included 4 items +by default: ‘session_id’, ‘ip_address’, ‘user_agent’, ‘last_activity’.

+

This was due to the specifics of how sessions worked, but is now no longer +necessary with our new implementation. However, it may happen that your +application relied on these values, so here are alternative methods of +accessing them:

+
+
    +
  • session_id: session_id()
    • +
  • ip_address: $_SERVER['REMOTE_ADDR']
    • +
  • user_agent: $this->input->user_agent() (unused by sessions)
    • +
  • last_activity: Depends on the storage, no straightforward way. Sorry!
    • +
+
+
+
+

Session Preferences

+

CodeIgniter will usually make everything work out of the box. However, +Sessions are a very sensitive component of any application, so some +careful configuration must be done. Please take your time to consider +all of the options and their effects.

+

You’ll find the following Session related preferences in your +application/config/config.php file:

+ ++++++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
PreferenceDefaultOptionsDescription
sess_driverfilesfiles/database/redis/memcached/customThe session storage driver to use.
sess_cookie_nameci_session[A-Za-z_-] characters onlyThe name used for the session cookie.
sess_expiration7200 (2 hours)Time in seconds (integer)The number of seconds you would like the session to last. +If you would like a non-expiring session (until browser is closed) set the value to zero: 0
sess_save_pathNULLNoneSpecifies the storage location, depends on the driver being used.
sess_match_ipFALSETRUE/FALSE (boolean)Whether to validate the user’s IP address when reading the session cookie. +Note that some ISPs dynamically changes the IP, so if you want a non-expiring session you +will likely set this to FALSE.
sess_time_to_update300Time in seconds (integer)This option controls how often the session class will regenerate itself and create a new +session ID. Setting it to 0 will disable session ID regeneration.
sess_regenerate_destroyFALSETRUE/FALSE (boolean)Whether to destroy session data associated with the old session ID when auto-regenerating +the session ID. When set to FALSE, the data will be later deleted by the garbage collector.
+
+

Note

+

As a last resort, the Session library will try to fetch PHP’s +session related INI settings, as well as legacy CI settings such as +‘sess_expire_on_close’ when any of the above is not configured. +However, you should never rely on this behavior as it can cause +unexpected results or be changed in the future. Please configure +everything properly.

+
+

In addition to the values above, the cookie and native drivers apply the +following configuration values shared by the Input and +Security classes:

+ +++++ + + + + + + + + + + + + + + + + + + + + +
PreferenceDefaultDescription
cookie_domain‘’The domain for which the session is applicable
cookie_path/The path to which the session is applicable
cookie_secureFALSEWhether to create the session cookie only on encrypted (HTTPS) connections
+
+

Note

+

The ‘cookie_httponly’ setting doesn’t have an effect on sessions. +Instead the HttpOnly parameter is always enabled, for security +reasons. Additionally, the ‘cookie_prefix’ setting is completely +ignored.

+
+
+
+

Session Drivers

+

As already mentioned, the Session library comes with 4 drivers, or storage +engines, that you can use:

+
+
    +
  • files
    • +
  • database
    • +
  • redis
    • +
  • memcached
    • +
+
+

By default, the Files Driver will be used when a session is initialized, +because it is the most safe choice and is expected to work everywhere +(virtually every environment has a file system).

+

However, any other driver may be selected via the $config['sess_driver'] +line in your application/config/config.php file, if you chose to do so. +Have it in mind though, every driver has different caveats, so be sure to +get yourself familiar with them (below) before you make that choice.

+

In addition, you may also create and use Custom Drivers, if the ones +provided by default don’t satisfy your use case.

+
+

Note

+

In previous CodeIgniter versions, a different, “cookie driver” +was the only option and we have received negative feedback on not +providing that option. While we do listen to feedback from the +community, we want to warn you that it was dropped because it is +unsafe and we advise you NOT to try to replicate it via a +custom driver.

+
+
+

Files Driver

+

The ‘files’ driver uses your file system for storing session data.

+

It can safely be said that it works exactly like PHP’s own default session +implementation, but in case this is an important detail for you, have it +mind that it is in fact not the same code and it has some limitations +(and advantages).

+

To be more specific, it doesn’t support PHP’s directory level and mode +formats used in session.save_path, +and it has most of the options hard-coded for safety. Instead, only +absolute paths are supported for $config['sess_save_path'].

+

Another important thing that you should know, is to make sure that you +don’t use a publicly-readable or shared directory for storing your session +files. Make sure that only you have access to see the contents of your +chosen sess_save_path directory. Otherwise, anybody who can do that, can +also steal any of the current sessions (also known as “session fixation” +attack).

+

On UNIX-like operating systems, this is usually achieved by setting the +0700 mode permissions on that directory via the chmod command, which +allows only the directory’s owner to perform read and write operations on +it. But be careful because the system user running the script is usually +not your own, but something like ‘www-data’ instead, so only setting those +permissions will probable break your application.

+

Instead, you should do something like this, depending on your environment

+
mkdir /<path to your application directory>/sessions/
+chmod 0700 /<path to your application directory>/sessions/
+chown www-data /<path to your application directory>/sessions/
+
+
+
+
Bonus Tip
+

Some of you will probably opt to choose another session driver because +file storage is usually slower. This is only half true.

+

A very basic test will probably trick you into believing that an SQL +database is faster, but in 99% of the cases, this is only true while you +only have a few current sessions. As the sessions count and server loads +increase - which is the time when it matters - the file system will +consistently outperform almost all relational database setups.

+

In addition, if performance is your only concern, you may want to look +into using tmpfs, +(warning: external resource), which can make your sessions blazing fast.

+
+
+
+

Database Driver

+

The ‘database’ driver uses a relational database such as MySQL or +PostgreSQL to store sessions. This is a popular choice among many users, +because it allows the developer easy access to the session data within +an application - it is just another table in your database.

+

However, there are some conditions that must be met:

+
+
    +
  • Only your default database connection (or the one that you access +as $this->db from your controllers) can be used.
    • +
  • You must have the Query Builder +enabled.
    • +
  • You can NOT use a persistent connection.
    • +
  • You can NOT use a connection with the cache_on setting enabled.
    • +
+
+

In order to use the ‘database’ session driver, you must also create this +table that we already mentioned and then set it as your +$config['sess_save_path'] value. +For example, if you would like to use ‘ci_sessions’ as your table name, +you would do this:

+
$config['sess_driver'] = 'database';
+$config['sess_save_path'] = 'ci_sessions';
+
+
+
+

Note

+

If you’ve upgraded from a previous version of CodeIgniter and +you don’t have ‘sess_save_path’ configured, then the Session +library will look for the old ‘sess_table_name’ setting and use +it instead. Please don’t rely on this behavior as it will get +removed in the future.

+
+

And then of course, create the database table …

+

For MySQL:

+
CREATE TABLE IF NOT EXISTS `ci_sessions` (
+        `id` varchar(128) NOT NULL,
+        `ip_address` varchar(45) NOT NULL,
+        `timestamp` int(10) unsigned DEFAULT 0 NOT NULL,
+        `data` blob NOT NULL,
+        KEY `ci_sessions_timestamp` (`timestamp`)
+);
+
+
+

For PostgreSQL:

+
CREATE TABLE "ci_sessions" (
+        "id" varchar(128) NOT NULL,
+        "ip_address" varchar(45) NOT NULL,
+        "timestamp" bigint DEFAULT 0 NOT NULL,
+        "data" text DEFAULT '' NOT NULL
+);
+
+CREATE INDEX "ci_sessions_timestamp" ON "ci_sessions" ("timestamp");
+
+
+

You will also need to add a PRIMARY KEY depending on your ‘sess_match_ip’ +setting. The examples below work both on MySQL and PostgreSQL:

+
// When sess_match_ip = TRUE
+ALTER TABLE ci_sessions ADD PRIMARY KEY (id, ip_address);
+
+// When sess_match_ip = FALSE
+ALTER TABLE ci_sessions ADD PRIMARY KEY (id);
+
+// To drop a previously created primary key (use when changing the setting)
+ALTER TABLE ci_sessions DROP PRIMARY KEY;
+
+
+
+

Important

+

Only MySQL and PostgreSQL databases are officially +supported, due to lack of advisory locking mechanisms on other +platforms. Using sessions without locks can cause all sorts of +problems, especially with heavy usage of AJAX, and we will not +support such cases. Use session_write_close() after you’ve +done processing session data if you’re having performance +issues.

+
+
+
+

Redis Driver

+
+

Note

+

Since Redis doesn’t have a locking mechanism exposed, locks for +this driver are emulated by a separate value that is kept for up +to 300 seconds.

+
+

Redis is a storage engine typically used for caching and popular because +of its high performance, which is also probably your reason to use the +‘redis’ session driver.

+

The downside is that it is not as ubiquitous as relational databases and +requires the phpredis PHP +extension to be installed on your system, and that one doesn’t come +bundled with PHP. +Chances are, you’re only be using the ‘redis’ driver only if you’re already +both familiar with Redis and using it for other purposes.

+

Just as with the ‘files’ and ‘database’ drivers, you must also configure +the storage location for your sessions via the +$config['sess_save_path'] setting. +The format here is a bit different and complicated at the same time. It is +best explained by the phpredis extension’s README file, so we’ll simply +link you to it:

+
+
+
+

Warning

+

CodeIgniter’s Session library does NOT use the actual ‘redis’ +session.save_handler. Take note only of the path format in +the link above.

+
+

For the most common case however, a simple host:port pair should be +sufficient:

+
$config['sess_driver'] = 'redis';
+$config['sess_save_path'] = 'tcp://localhost:6379';
+
+
+
+
+

Memcached Driver

+
+

Note

+

Since Memcache doesn’t have a locking mechanism exposed, locks +for this driver are emulated by a separate value that is kept for +up to 300 seconds.

+
+

The ‘memcached’ driver is very similar to the ‘redis’ one in all of its +properties, except perhaps for availability, because PHP’s Memcached extension is distributed via PECL and some +Linux distrubutions make it available as an easy to install package.

+

Other than that, and without any intentional bias towards Redis, there’s +not much different to be said about Memcached - it is also a popular +product that is usually used for caching and famed for its speed.

+

However, it is worth noting that the only guarantee given by Memcached +is that setting value X to expire after Y seconds will result in it being +deleted after Y seconds have passed (but not necessarily that it won’t +expire earlier than that time). This happens very rarely, but should be +considered as it may result in loss of sessions.

+

The $config['sess_save_path'] format is fairly straightforward here, +being just a host:port pair:

+
$config['sess_driver'] = 'memcached';
+$config['sess_save_path'] = 'localhost:11211';
+
+
+
+
Bonus Tip
+

Multi-server configuration with an optional weight parameter as the +third colon-separated (:weight) value is also supported, but we have +to note that we haven’t tested if that is reliable.

+

If you want to experiment with this feature (on your own risk), simply +separate the multiple server paths with commas:

+
// localhost will be given higher priority (5) here,
+// compared to 192.0.2.1 with a weight of 1.
+$config['sess_save_path'] = 'localhost:11211:5,192.0.2.1:11211:1';
+
+
+
+
+
+

Custom Drivers

+

You may also create your own, custom session drivers. However, have it in +mind that this is typically not an easy task, as it takes a lot of +knowledge to do it properly.

+

You need to know not only how sessions work in general, but also how they +work specifically in PHP, how the underlying storage mechanism works, how +to handle concurrency, avoid deadlocks (but NOT through lack of locks) and +last but not least - how to handle the potential security issues, which +is far from trivial.

+

Long story short - if you don’t know how to do that already in raw PHP, +you shouldn’t be trying to do it within CodeIgniter either. You’ve been +warned.

+

If you only want to add some extra functionality to your sessions, just +extend the base Session class, which is a lot more easier. Read the +Creating Libraries article to +learn how to do that.

+

Now, to the point - there are three general rules that you must follow +when creating a session driver for CodeIgniter:

+
+
    +

  • Put your driver’s file under application/libraries/Session/drivers/ +and follow the naming conventions used by the Session class.

    +

    For example, if you were to create a ‘dummy’ driver, you would have +a Session_dummy_driver class name, that is declared in +application/libraries/Session/drivers/Session_dummy_driver.php.

    +
    • +

  • Extend the CI_Session_driver class.

    +

    This is just a basic class with a few internal helper methods. It is +also extendable like any other library, if you really need to do that, +but we are not going to explain how … if you’re familiar with how +class extensions/overrides work in CI, then you already know how to do +it. If not, well, you shouldn’t be doing it in the first place.

    +
    • +

  • Implement the SessionHandlerInterface interface.

    +
    +

    Note

    +

    You may notice that SessionHandlerInterface is provided +by PHP since version 5.4.0. CodeIgniter will automatically declare +the same interface if you’re running an older PHP version.

    +
    +

    The link will explain why and how.

    +
    • +
+
+

So, based on our ‘dummy’ driver example above, you’d end up with something +like this:

+
// application/libraries/Session/drivers/Session_dummy_driver.php:
+
+class CI_Session_dummy_driver extends CI_Session_driver implements SessionHandlerInterface
+{
+
+        public function __construct(&$params)
+        {
+                // DO NOT forget this
+                parent::__construct($params);
+
+                // Configuration & other initializations
+        }
+
+        public function open($save_path, $name)
+        {
+                // Initialize storage mechanism (connection)
+        }
+
+        public function read($session_id)
+        {
+                // Read session data (if exists), acquire locks
+        }
+
+        public function write($session_id, $session_data)
+        {
+                // Create / update session data (it might not exist!)
+        }
+
+        public function close()
+        {
+                // Free locks, close connections / streams / etc.
+        }
+
+        public function destroy($session_id)
+        {
+                // Call close() method & destroy data for current session (order may differ)
+        }
+
+        public function gc($maxlifetime)
+        {
+                // Erase data for expired sessions
+        }
+
+}
+
+
+

If you’ve done everything properly, you can now set your sess_driver +configuration value to ‘dummy’ and use your own driver. Congratulations!

+
+
+
+
+

Class Reference

+
+
+class CI_Session
+
+
+userdata([$key = NULL])
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Session item key or NULL
    • +
+
Returns:

Value of the specified item key, or an array of all userdata

+
Return type:

mixed

+
+

Gets the value for a specific $_SESSION item, or an +array of all “userdata” items if not key was specified.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. You should +directly access $_SESSION instead.

+
+
+ +
+
+all_userdata()
+
+++ + + + + + +
Returns:An array of all userdata
Return type:array
+

Returns an array containing all “userdata” items.

+
+

Note

+

This method is DEPRECATED. Use userdata() +with no parameters instead.

+
+
+ +
+
+&get_userdata()
+
+++ + + + + + +
Returns:A reference to $_SESSION
Return type:array
+

Returns a reference to the $_SESSION array.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications.

+
+
+ +
+
+has_userdata($key)
+
+++ + + + + + + + +
Parameters:
    +
  • $key (string) – Session item key
    • +
+
Returns:

TRUE if the specified key exists, FALSE if not

+
Return type:

bool

+
+

Checks if an item exists in $_SESSION.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. It is just +an alias for isset($_SESSION[$key]) - please +use that instead.

+
+
+ +
+
+set_userdata($data[, $value = NULL])
+
+++ + + + + + +
Parameters:
    +
  • $data (mixed) – An array of key/value pairs to set as session data, or the key for a single item
    • +
  • $value (mixed) – The value to set for a specific session item, if $data is a key
    • +
+
Return type:

void

+
+

Assigns data to the $_SESSION superglobal.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications.

+
+
+ +
+
+unset_userdata($key)
+
+++ + + + + + +
Parameters:
    +
  • $key (mixed) – Key for the session data item to unset, or an array of multiple keys
    • +
+
Return type:

void

+
+

Unsets the specified key(s) from the $_SESSION +superglobal.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. It is just +an alias for unset($_SESSION[$key]) - please +use that instead.

+
+
+ +
+
+mark_as_flash($key)
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Key to mark as flashdata, or an array of multiple keys
    • +
+
Returns:

TRUE on success, FALSE on failure

+
Return type:

bool

+
+

Marks a $_SESSION item key (or multiple ones) as +“flashdata”.

+
+ +
+
+get_flash_keys()
+
+++ + + + + + +
Returns:Array containing the keys of all “flashdata” items.
Return type:array
+

Gets a list of all $_SESSION that have been marked as +“flashdata”.

+
+ +
+
+unmark_flash($key)
+
+++ + + + + + +
Parameters:
    +
  • $key (mixed) – Key to be un-marked as flashdata, or an array of multiple keys
    • +
+
Return type:

void

+
+

Unmarks a $_SESSION item key (or multiple ones) as +“flashdata”.

+
+ +
+
+flashdata([$key = NULL])
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Flashdata item key or NULL
    • +
+
Returns:

Value of the specified item key, or an array of all flashdata

+
Return type:

mixed

+
+

Gets the value for a specific $_SESSION item that has +been marked as “flashdata”, or an array of all “flashdata” +items if no key was specified.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. You should +directly access $_SESSION instead.

+
+
+ +
+
+keep_flashdata($key)
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Flashdata key to keep, or an array of multiple keys
    • +
+
Returns:

TRUE on success, FALSE on failure

+
Return type:

bool

+
+

Retains the specified session data key(s) as “flashdata” +through the next request.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. It is just +an alias for the mark_as_flash() method.

+
+
+ +
+
+set_flashdata($data[, $value = NULL])
+
+++ + + + + + +
Parameters:
    +
  • $data (mixed) – An array of key/value pairs to set as flashdata, or the key for a single item
    • +
  • $value (mixed) – The value to set for a specific session item, if $data is a key
    • +
+
Return type:

void

+
+

Assigns data to the $_SESSION superglobal and marks it +as “flashdata”.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications.

+
+
+ +
+
+mark_as_temp($key[, $ttl = 300])
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Key to mark as tempdata, or an array of multiple keys
    • +
  • $ttl (int) – Time-to-live value for the tempdata, in seconds
    • +
+
Returns:

TRUE on success, FALSE on failure

+
Return type:

bool

+
+

Marks a $_SESSION item key (or multiple ones) as +“tempdata”.

+
+ +
+
+get_temp_keys()
+
+++ + + + + + +
Returns:Array containing the keys of all “tempdata” items.
Return type:array
+

Gets a list of all $_SESSION that have been marked as +“tempdata”.

+
+ +
+
+unmark_temp($key)
+
+++ + + + + + +
Parameters:
    +
  • $key (mixed) – Key to be un-marked as tempdata, or an array of multiple keys
    • +
+
Return type:

void

+
+

Unmarks a $_SESSION item key (or multiple ones) as +“tempdata”.

+
+ +
+
+tempdata([$key = NULL])
+
+++ + + + + + + + +
Parameters:
    +
  • $key (mixed) – Tempdata item key or NULL
    • +
+
Returns:

Value of the specified item key, or an array of all tempdata

+
Return type:

mixed

+
+

Gets the value for a specific $_SESSION item that has +been marked as “tempdata”, or an array of all “tempdata” +items if no key was specified.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications. You should +directly access $_SESSION instead.

+
+
+ +
+
+set_tempdata($data[, $value = NULL])
+
+++ + + + + + +
Parameters:
    +
  • $data (mixed) – An array of key/value pairs to set as tempdata, or the key for a single item
    • +
  • $value (mixed) – The value to set for a specific session item, if $data is a key
    • +
  • $ttl (int) – Time-to-live value for the tempdata item(s), in seconds
    • +
+
Return type:

void

+
+

Assigns data to the $_SESSION superglobal and marks it +as “tempdata”.

+
+

Note

+

This is a legacy method kept only for backwards +compatibility with older applications.

+
+
+ +
+
+sess_regenerate([$destroy = FALSE])
+
+++ + + + + + +
Parameters:
    +
  • $destroy (bool) – Whether to destroy session data
    • +
+
Return type:

void

+
+

Regenerate session ID, optionally destroying the current +session’s data.

+
+

Note

+

This method is just an alias for PHP’s native +session_regenerate_id() function.

+
+
+ +
+
+sess_destroy()
+
+++ + + + +
Return type:void
+

Destroys the current session.

+
+

Note

+

This must be the last session-related function +that you call. All session data will be lost after +you do that.

+
+
+

Note

+

This method is just an alias for PHP’s native +session_destroy() function.

+
+
+ +
+
+__get($key)
+
+++ + + + + + + + +
Parameters:
    +
  • $key (string) – Session item key
    • +
+
Returns:

The requested session data item, or NULL if it doesn’t exist

+
Return type:

mixed

+
+

A magic method that allows you to use +$this->session->item instead of $_SESSION['item'], +if that’s what you prefer.

+

It will also return the session ID by calling +session_id() if you try to access +$this->session->session_id.

+
+ +
+
+__set($key, $value)
+
+++ + + + + + +
Parameters:
    +
  • $key (string) – Session item key
    • +
  • $value (mixed) – Value to assign to the session item key
    • +
+
Returns:

void

+
+

A magic method that allows you to assign items to +$_SESSION by accessing them as $this->session +properties:

+
$this->session->foo = 'bar';
+
+// Results in:
+// $_SESSION['foo'] = 'bar';
+
+
+
+ +
+ +
+
+ + +