时域库 | Session Library

Session Library

Session类允许您在浏览您的网站时维护用户的“状态”并跟踪他们的活动。

CodeIgniter带有几个会话存储驱动程序：

• 文件（默认;基于文件系统）

另外，您可以基于其他类型的存储创建自己的自定义会话驱动程序，同时仍然利用Session类的功能。

• 使用会话类

- [What is Session Data?](about:blank#what-is-session-data)
- [Retrieving Session Data](about:blank#retrieving-session-data)
- [Adding Session Data](about:blank#adding-session-data)
- [Removing Session Data](about:blank#removing-session-data)
- [Flashdata](about:blank#flashdata)
- [Tempdata](about:blank#tempdata)
- [Destroying a Session](about:blank#destroying-a-session)
- [Accessing session metadata](about:blank#accessing-session-metadata)
- [Session Preferences](about:blank#session-preferences)
-  [Session Drivers](about:blank#session-drivers)
    -  [Files Driver](about:blank#files-driver)
        - [Bonus Tip](about:blank#bonus-tip)

    - [Database Driver](about:blank#database-driver)
    - [Redis Driver](about:blank#redis-driver)
    -  [Memcached Driver](about:blank#memcached-driver)
        - [Bonus Tip](about:blank#id1)

    - [Custom Drivers](about:blank#custom-drivers)

• 类参考

使用会话类

初始化会话

会话通常会在每次页面加载时全局运行，因此Session类应该在控制器构造函数中初始化，或者可以由系统自动加载。在大多数情况下，会话类将在后台无人值守运行，因此只需初始化该类就可以在必要时读取，创建和更新会话。

要在控制器构造函数中手动初始化Session类，请使用以下$this->load->library()方法：

$this->load->library('session'

加载后，会话库对象将可用：

$this->session

重要

由于Loader类是由CodeIgniter的基本控制器实例化的，因此请务必parent::__construct()在尝试从控制器构造函数中加载库之前进行调用。

会话如何工作？

加载页面时，会话类将检查用户浏览器是否发送有效的会话cookie。如果会话Cookie并不不存在（或者如果它不匹配一个存储在服务器上或已过期）的新会话将被创建和保存。

如果有效的会话存在，其信息将被更新。每次更新时，如果配置为这样，会话ID可能会重新生成。

了解一旦初始化后，Session类自动运行对你来说很重要。没有什么你需要做的，导致上述行为发生。正如您将在下面看到的，您可以使用会话数据，但读取，写入和更新会话的过程是自动的。

注意

在CLI下，会话库将自动停止，因为这是一个完全基于HTTP协议的概念。

关于并发性的说明

除非你正在开发一个AJAX用量很大的网站，否则你可以跳过这一节。但是，如果你是，而且如果你遇到性能问题，那么这个笔记就是你正在寻找的东西。

以前版本的CodeIgniter中的会话没有实现锁定，这意味着使用同一会话的两个HTTP请求可以同时运行。要使用更合适的技术术语 - 请求是非阻塞的。

但是，会话上下文中的非阻塞请求也意味着不安全，因为在一个请求中修改会话数据（或会话ID再生）可能会干扰第二个并发请求的执行。这个细节是许多问题的根源，也是CodeIgniter 3.0有一个完全重写的会话库的主要原因。

我们为什么要告诉你这个？因为很可能在找到性能问题的原因之后，可能会得出结论：锁定是问题，因此需要研究如何删除锁定...

不要那样做！删除锁将是错误的，它会导致更多的问题！

锁定不是问题，它是一个解决方案。你的问题是，你仍然打开会议，而你已经处理它，因此不再需要它。所以，你需要的是在你不再需要之后关闭当前请求的会话。

长话短说 - session_write_close()一旦你不再需要任何与会话变量有关的事情，就会致电。

什么是会话数据？

会话数据只是一个与特定会话ID（cookie）关联的数组。

如果您以前在PHP中使用会话，则应该熟悉PHP的$ _SESSION超全局（如果没有，请阅读该链接上的内容）。

CodeIgniter通过相同的方式访问会话数据，因为它使用PHP提供的会话处理器机制。使用会话数据与操作（读取，设置和取消设置值）$_SESSION数组一样简单。

另外，CodeIgniter还提供了2种特殊类型的会话数据，这些数据将在下面进一步解释：flashdata和tempdata。

注意

在以前的版本中，CodeIgniter中的常规会话数据被称为'userdata'。请记住，如果该术语在手册的其他地方使用。它的大部分内容都是为了解释自定义的'userdata'方法是如何工作的。

检索会话数据

来自会话数组的任何信息都可以通过$_SESSION超全局获得：

$_SESSION['item']

或者通过魔术获得者：

$this->session->item

为了向后兼容，通过以下userdata()方法：

$this->session->userdata('item'

其中item是与您希望获取的物品相对应的数组键。例如，要将以前存储的'名称'项目分配给$name变量，您将执行以下操作：

$name = $_SESSION['name'];

// or:

$name = $this->session->name

// or:

$name = $this->session->userdata('name'

注意

userdata()如果您尝试访问的项目不存在，则该方法返回NULL。

如果你想检索所有现有的用户数据，你可以简单地省略项目键（魔术获得者只适用于属性）：

$_SESSION

// or:

$this->session->userdata(

添加会话数据

比方说，一个特定的用户登录到您的网站。一旦通过身份验证，您就可以将他们的用户名和电子邮件地址添加到会话中，使您可以在全球范围内使用这些数据，而无需在需要时运行数据库查询。

$_SESSION与任何其他变量一样，您可以简单地将数据分配给数组。或作为一个属性$this->session。

或者，也可以使用将其分配为“用户数据”的旧方法。但是，将包含新数据的数组传递给set_userdata()方法：

$this->session->set_userdata($array

$array包含新数据的关联数组在哪里？这是一个例子：

$newdata = array(
        'username'  => 'johndoe',
        'email'     => '[email protected]',
        'logged_in' => TRUE


$this->session->set_userdata($newdata

如果您想一次添加userdata一个值，set_userdata()还支持以下语法：

$this->session->set_userdata('some_name', 'some_value'

如果您想验证会话值是否存在，只需检查isset()：

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

或者你可以打电话给has_userdata()：

$this->session->has_userdata('some_name'

删除会话数据

正如其他任何变量一样，$_SESSION可以通过unset()以下方式取消设置值：

unset($_SESSION['some_name']

// or multiple values:

unset(
        $_SESSION['some_name'],
        $_SESSION['another_name']

此外，正如set_userdata()可以用来向会话添加信息一样，unset_userdata()可以通过传递会话密钥来删除它。例如，如果您想从会话数据数组中删除'some_name'：

$this->session->unset_userdata('some_name'

该方法还接受一组项目键以取消设置：

$array_items = array('username', 'email'

$this->session->unset_userdata($array_items

注意

在以前的版本中，该unset_userdata()方法用于接受一个关联数组key => 'dummy value'对。这不再支持。

Flashdata

CodeIgniter支持“flashdata”或会话数据，它们只会在下一个请求中使用，然后自动清除。

这可能非常有用，特别是对于一次性信息，错误或状态消息（例如：“记录2已删除”）。

应该注意的是，flashdata变量是常规会话变量，只有在'__ci_vars'键下以特定方式标记（请不要触摸那个，你已被警告过）。

将现有项目标记为“flashdata”：

$this->session->mark_as_flash('item'

如果您想将多个项目标记为flashdata，只需将密钥作为数组传递即可：

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

添加flashdata：

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

或者，使用该set_flashdata()方法：

$this->session->set_flashdata('item', 'value'

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

读取flashdata变量与读取常规会话数据的过程相同$_SESSION：

$_SESSION['item']

重要

该userdata()方法不会返回flashdata项目。

但是，如果您想确定您正在阅读“flashdata”（而不是其他类型），则还可以使用以下flashdata()方法：

$this->session->flashdata('item'

或者为了获得一个包含所有flash数据的数组，只需省略关键参数：

$this->session->flashdata(

注意

flashdata()如果无法找到该项目，该方法返回NULL。

如果您发现需要通过附加请求保留flashdata变量，则可以使用该keep_flashdata()方法执行此操作。您可以传递单个项目或一组flash数据项以保留。

$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()

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:

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:

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

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.

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:

https://github.com/phpredis/phpredis#php-session-handler

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.

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_Sessionuserdata([$key = NULL])

• $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()

&get_userdata()

has_userdata($key)

• $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])

• $data (mixed) – An array of key/value pairs to set as session data, or the key for a single item

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)

• $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)

• $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()

unmark_flash($key)

• $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])

• $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)

• $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])

• $data (mixed) – An array of key/value pairs to set as flashdata, or the key for a single item

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])

• $key (mixed) – Key to mark as tempdata, 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 “tempdata”.

get_temp_keys()

unmark_temp($key)

• $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])

• $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])

• $data (mixed) – An array of key/value pairs to set as tempdata, or the key for a single item

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])

• $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()

__get($key)

• $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)

• $key (string) – 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';

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Licensed under the MIT License.

https://www.codeigniter.com/user_guide/libraries/sessions.html