版本：laravel 9

摘要

• 單一資料表，新增 is_admin 欄位。
• 建立middleware: IsAdmin。
• 不需要額外的guard。登出的時候由於是單一資料表，登出就是登出了，所以不需要像兩張表那樣，判斷是前台 web guard 還是後台 admin guard。

修改 database\migrations\2014_10_12_000000_create_users_table.php
增加一欄

$table->boolean('is_admin')->nullable();

修改 database\seeders\DatabaseSeeder.php

    public function run()
    {
        \App\Models\User::factory()->create([
            'name' => 'Administrator',
            'email' => 'admin@example.com',
            'password' => bcrypt('123456'),
            'is_admin' => '1',
        ]);
    }

修改 app\Models\User.php

protected $fillable = [
...
    'is_admin'
];

建立 middleware
php artisan make:middleware IsAdmin
app\Http\Middleware\IsAdmin.php

    public function handle(Request $request, Closure $next)
    {
        //return $next($request);
        
        if(auth()->user()->is_admin == 1){
            return $next($request);
        }
        return redirect('home')->with('error',"Only admin can access!");
    }

修改 app/Http/Kernel.php

    protected $routeMiddleware = [
        ...
        'is_admin' => \App\Http\Middleware\IsAdmin::class,
    ];

建立 DashboardController
後台首頁通常叫做 dashboard
php make:controller Admin

    public function index()
    {
        return view('admin.dashboard');
    }

修改 routes/web.php

<?php
use Illuminate\Support\Facades\Route;
use App\Http\Controllers\HomeController;
use App\Http\Controllers\Admin\DashboardController;

Route::get('/', function () {
    return view('welcome');
});

Auth::routes();

Route::get('/home', [HomeController::class, 'index'])->name('home');

Route::group(['prefix' => 'admin', 'middleware' => 'is_admin'], function () {
    Route::get('/', [DashboardController::class, 'index'])->name('admin.dashboard');
    // other admin routes...
});

建立 views/admin/_layouts/app.blade.php
內容複製 views/layouts/app.blade.php

建立 views/admin/dashboard.blade.php
內容複製 views/home.blade.php

是否修改 app/Http/Controllers/Auth/LoginController.php ？
網路上有的做法會重寫 login()，如果 is_admin==1 則導向後台。但我覺得應該不需要。單一登入用的就是前台的登入，既然如此，前台登入就導向前台首頁，合理。若要進入後台，應該是在頁面上提供後台連結。下面供參考。

    public function login(Request $request)
    {
        $request->validate([
            'email'     => 'required|email',
            'password'  => 'required'
        ]);

        $credentials = $request->only('email', 'password');

        if(! auth()->attempt($credentials)){
            return redirect()->route('login')
                ->with('error','Email-Address or Password not correct.');
        }

        if (auth()->user()->is_admin == 1) {
            return redirect()->route('admin.dashboard');
        }

        return redirect()->route('home');
    }

參考文章
https://codingdriver.com/laravel-multi-auth-authentication-tutorial-example.html
使用 middleware, IsAdmin

https://www.itsolutionstuff.com/post/laravel-9-multi-auth-create-multiple-authentication-in-laravelexample.html
使用 middleware, UserAccess，可以有不同身份。但是一般來說用不到不同身份，大部份都是拆分前後台，前台user，後台就 admin，然後再設定權限。