laravel 5.3 想辦法變成multi版，利用middlewaare

一、修改 .env
增加，0為單機版；1為multi版

MULTI_SERVER=1

二、新增一個 middleware

php artisan make:middleware MultiMiddleware

修改它

...
    public function handle($request, Closure $next)
    {
      if(!isset($_SESSION)) session_start();
      if(env('MULTI_SERVER')=='0') $_SESSION['schoolDB'] = env('DB_DATABASE', 'forge');
      if(env('MULTI_SERVER')=='1'){
        if(empty($_SESSION['schoolDB'])){
          $_SESSION['schoolDB']="";
          return redirect('school_list');
        }
      }
      return $next($request);
    }
}

...

註冊此middleware
在 ./app/Http/下修改kernel.php，增加一個multi的類別

    protected $routeMiddleware = [
        'auth' => \Illuminate\Auth\Middleware\Authenticate::class,
        'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
        'bindings' => \Illuminate\Routing\Middleware\SubstituteBindings::class,
        'can' => \Illuminate\Auth\Middleware\Authorize::class,
        'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
        'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
        'admin' => \App\Http\Middleware\AdminMiddleware::class,
        'multi' => \App\Http\Middleware\MultiMiddleware::class,
    ];

三、修改 ./config/database.php
//第1行加入

<?php
if(!isset($_SESSION)) session_start();
$schoolDB = $_SESSION['schoolDB'];
...

//約58行處，改成以下

...
'database' => $schoolDB,
...

四、做一個選擇學校的 route 及 view
route
修改web.php

//在根目錄下，用multi這個middleware驗證資料庫
Route::get('/', function () {
    return view ('welcome');
})->middleware(multi::class);

//或是用group，底下的route都要這個驗證
Route::group(['middleware' => 'multi'],function(){
  Route::get('/admin', function () {
      ...
  });
});

//選擇學校的route
Route::get('school_list',function(){
  return view('school_list');
});

//處理該校的資料庫
Route::get('school/{schoolDB}',function($schoolDB){
  if(!isset($_SESSION)) session_start();
  $_SESSION['schoolDB'] = $schoolDB;
  return redirect('/');
});

view
新增一個 school_list.blade.php

每個連結到  /school/074xxx