Сессии
Introduction
Since HTTP driven applications are stateless, sessions provide a way to store information about the user across multiple requests. Laravel ships with a variety of session backends that are accessed through an expressive, unified API. Support for popular backends such as Memcached, Redis, and databases is included out of the box.
Configuration
The session configuration file is stored at config/session.php
. Be sure to review the options available to you in this file. By default, Laravel is configured to use the file
session driver, which will work well for many applications.
The session driver
configuration option defines where session data will be stored for each request. Laravel ships with several great drivers out of the box:
file
- sessions are stored instorage/framework/sessions
.cookie
- sessions are stored in secure, encrypted cookies.database
- sessions are stored in a relational database.memcached
/redis
- sessions are stored in one of these fast, cache based stores.array
- sessions are stored in a PHP array and will not be persisted.
The array driver is used during testing and prevents the data stored in the session from being persisted.
Driver Prerequisites
Database
When using the database
session driver, you will need to create a table to contain the session items. Below is an example Schema
declaration for the table:
You may use the session:table
Artisan command to generate this migration:
Redis
Before using Redis sessions with Laravel, you will need to either install the PhpRedis PHP extension via PECL or install the predis/predis
package (~1.0) via Composer. For more information on configuring Redis, consult its Laravel documentation page.
In the
session
configuration file, theconnection
option may be used to specify which Redis connection is used by the session.
Using The Session
Retrieving Data
There are two primary ways of working with session data in Laravel: the global session
helper and via a Request
instance. First, let's look at accessing the session via a Request
instance, which can be type-hinted on a controller method. Remember, controller method dependencies are automatically injected via the Laravel service container:
When you retrieve an item from the session, you may also pass a default value as the second argument to the get
method. This default value will be returned if the specified key does not exist in the session. If you pass a Closure
as the default value to the get
method and the requested key does not exist, the Closure
will be executed and its result returned:
The Global Session Helper
You may also use the global session
PHP function to retrieve and store data in the session. When the session
helper is called with a single, string argument, it will return the value of that session key. When the helper is called with an array of key / value pairs, those values will be stored in the session:
There is little practical difference between using the session via an HTTP request instance versus using the global
session
helper. Both methods are testable via theassertSessionHas
method which is available in all of your test cases.
Retrieving All Session Data
If you would like to retrieve all the data in the session, you may use the all
method:
Determining If An Item Exists In The Session
To determine if an item is present in the session, you may use the has
method. The has
method returns true
if the item is present and is not null
:
To determine if an item is present in the session, even if its value is null
, you may use the exists
method. The exists
method returns true
if the item is present:
Storing Data
To store data in the session, you will typically use the put
method or the session
helper:
Pushing To Array Session Values
The push
method may be used to push a new value onto a session value that is an array. For example, if the user.teams
key contains an array of team names, you may push a new value onto the array like so:
Retrieving & Deleting An Item
The pull
method will retrieve and delete an item from the session in a single statement:
Flash Data
Sometimes you may wish to store items in the session only for the next request. You may do so using the flash
method. Data stored in the session using this method will be available immediately and during the subsequent HTTP request. After the subsequent HTTP request, the flashed data will be deleted. Flash data is primarily useful for short-lived status messages:
If you need to keep your flash data around for several requests, you may use the reflash
method, which will keep all of the flash data for an additional request. If you only need to keep specific flash data, you may use the keep
method:
Deleting Data
The forget
method will remove a piece of data from the session. If you would like to remove all data from the session, you may use the flush
method:
Regenerating The Session ID
Regenerating the session ID is often done in order to prevent malicious users from exploiting a session fixation attack on your application.
Laravel automatically regenerates the session ID during authentication if you are using the built-in LoginController
; however, if you need to manually regenerate the session ID, you may use the regenerate
method.
Session Blocking
To utilize session blocking, your application must be using a cache driver that supports atomic locks. Currently, those cache drivers include the
memcached
,dynamodb
,redis
, anddatabase
drivers. In addition, you may not use thecookie
session driver.
By default, Laravel allows requests using the same session to execute concurrently. So, for example, if you use a JavaScript HTTP library to make two HTTP requests to your application, they will both execute at the same time. For many applications, this is not a problem; however, session data loss can occur in a small subset of applications that make concurrent requests to two different application endpoints which both write data to the session.
To mitigate this, Laravel provides functionality that allows you to limit concurrent requests for a given session. To get started, you may simply chain the block
method onto your route definition. In this example, an incoming request to the /profile
endpoint would acquire a session lock. While this lock is being held, any incoming requests to the /profile
or /order
endpoints which share the same session ID will wait for the first request to finish executing before continuing their execution:
The block
method accepts two optional arguments. The first argument accepted by the block
method is the maximum number of seconds the session lock should be held for before it is released. Of course, if the request finishes executing before this time the lock will be released earlier.
The second argument accepted by the block
method is the number of seconds a request should wait while attempting to obtain a session lock. A Illuminate\Contracts\Cache\LockTimoutException
will be thrown if the request is unable to obtain a session lock within the given number of seconds.
If neither of these arguments are passed, the lock will be obtained for a maximum of 10 seconds and requests will wait a maximum of 10 seconds while attempting to obtain a lock:
Adding Custom Session Drivers
Implementing The Driver
Your custom session driver should implement the SessionHandlerInterface
. This interface contains just a few simple methods we need to implement. A stubbed MongoDB implementation looks something like this:
Laravel does not ship with a directory to contain your extensions. You are free to place them anywhere you like. In this example, we have created an
Extensions
directory to house theMongoSessionHandler
.
Since the purpose of these methods is not readily understandable, let's quickly cover what each of the methods do:
The
open
method would typically be used in file based session store systems. Since Laravel ships with afile
session driver, you will almost never need to put anything in this method. You can leave it as an empty stub. It is a fact of poor interface design (which we'll discuss later) that PHP requires us to implement this method.The
close
method, like theopen
method, can also usually be disregarded. For most drivers, it is not needed.The
read
method should return the string version of the session data associated with the given$sessionId
. There is no need to do any serialization or other encoding when retrieving or storing session data in your driver, as Laravel will perform the serialization for you.The
write
method should write the given$data
string associated with the$sessionId
to some persistent storage system, such as MongoDB, Dynamo, etc. Again, you should not perform any serialization - Laravel will have already handled that for you.The
destroy
method should remove the data associated with the$sessionId
from persistent storage.The
gc
method should destroy all session data that is older than the given$lifetime
, which is a UNIX timestamp. For self-expiring systems like Memcached and Redis, this method may be left empty.
Registering The Driver
Once your driver has been implemented, you are ready to register it with the framework. To add additional drivers to Laravel's session backend, you may use the extend
method on the Session
facade. You should call the extend
method from the boot
method of a service provider. You may do this from the existing AppServiceProvider
or create an entirely new provider:
Once the session driver has been registered, you may use the mongo
driver in your config/session.php
configuration file.
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