Laravel Session

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.
sessionも色々な使い方があるようです。なるほど、これは勉強になります。

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. In production applications, you may consider using the memcached or redis drivers for even faster session performance.

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 in storage/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.
まず、config/session.phpを見てみたいと思います。
項目があまりないです。

'cookie' => env(
        'SESSION_COOKIE',
        str_slug(env('APP_NAME', 'laravel'), '_').'_session'
    ),

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:

Schema::create('sessions', function ($table) {
    $table->string('id')->unique();
    $table->unsignedInteger('user_id')->nullable();
    $table->string('ip_address', 45)->nullable();
    $table->text('user_agent')->nullable();
    $table->text('payload');
    $table->integer('last_activity');
});

uniqe, nullableはわかる。primary keyは自動か？

You may use the session:table Artisan command to generate this migration:

php artisan session:table
php artisan migrate

Redis
Before using Redis sessions with Laravel, you will need to install the predis/predis package (~1.0) via Composer. You may configure your Redis connections in the database configuration file. In the session configuration file, the connection 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:

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Http\Controllers\Controller;

class UserController extends Controller
{
    /**
     * Show the profile for the given user.
     *
     * @param  Request  $request
     * @param  int  $id
     * @return Response
     */
    public function show(Request $request, $id)
    {
        $value = $request->session()->get('key');

        //
    }
}

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:

Route::get('home', function () {
    // Retrieve a piece of data from the session...
    $value = session('key');

    // Specifying a default value...
    $value = session('key', 'default');

    // Store a piece of data in the session...
    session(['key' => 'value']);
});

Retrieving All Session Data
If you would like to retrieve all the data in the session, you may use the all method:

$data = $request->session()->all();

Storing Data
To store data in the session, you will typically use the put method or the session helper:

// Via a request instance...
$request->session()->put('key', 'value');

// Via the global helper...
session(['key' => 'value']);

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:

$request->session()->push('user.teams', 'developers');

Retrieving & Deleting An Item
The pull method will retrieve and delete an item from the session in a single statement:

$value = $request->session()->pull('key', 'default');

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 only be available during the subsequent HTTP request, and then will be deleted. Flash data is primarily useful for short-lived status messages:

$request->session()->flash('status', 'Task was successful!');

Adding Custom Session Drivers

namespace App\Extensions;

class MongoSessionHandler implements \SessionHandlerInterface
{
    public function open($savePath, $sessionName) {}
    public function close() {}
    public function read($sessionId) {}
    public function write($sessionId, $data) {}
    public function destroy($sessionId) {}
    public function gc($lifetime) {}
}

namespace App\Providers;

use App\Extensions\MongoSessionHandler;
use Illuminate\Support\Facades\Session;
use Illuminate\Support\ServiceProvider;

class SessionServiceProvider extends ServiceProvider
{
    /**
     * Perform post-registration booting of services.
     *
     * @return void
     */
    public function boot()
    {
        Session::extend('mongo', function ($app) {
            // Return implementation of SessionHandlerInterface...
            return new MongoSessionHandler;
        });
    }

    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}