creating a custom authentication system in laravel - laravel

How can I build an authentication system for customer?
I have used laravel built in authentication system for my admin panel where built in user model and users table already used.
Now I want to build another authentication system for my customer where customer model and customers table will be used.
How can I do this in laravel 5.2 ?

How to implement Multi Auth in Larvel 5.2
As Mentioned above. Two table admin and users
Laravel 5.2 has a new artisan command.
php artisan make:auth
it will generate basic login/register route, view and controller for user table.
Make a admin table as users table for simplicity.
Controller For Admin
app/Http/Controllers/AdminAuth/AuthController
app/Http/Controllers/AdminAuth/PasswordController
(note: I just copied these files from app/Http/Controllers/Auth/AuthController here)
config/auth.php
//Authenticating guards
'guards' => [
'user' =>[
'driver' => 'session',
'provider' => 'user',
],
'admin' => [
'driver' => 'session',
'provider' => 'admin',
],
],
//User Providers
'providers' => [
'user' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
]
],
//Resetting Password
'passwords' => [
'clients' => [
'provider' => 'client',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
'admins' => [
'provider' => 'admin',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
],
route.php
Route::group(['middleware' => ['web']], function () {
//Login Routes...
Route::get('/admin/login','AdminAuth\AuthController#showLoginForm');
Route::post('/admin/login','AdminAuth\AuthController#login');
Route::get('/admin/logout','AdminAuth\AuthController#logout');
// Registration Routes...
Route::get('admin/register', 'AdminAuth\AuthController#showRegistrationForm');
Route::post('admin/register', 'AdminAuth\AuthController#register');
Route::get('/admin', 'AdminController#index');
});
AdminAuth/AuthController.php
Add two methods and specify $redirectTo and $guard
protected $redirectTo = '/admin';
protected $guard = 'admin';
public function showLoginForm()
{
if (view()->exists('auth.authenticate')) {
return view('auth.authenticate');
}
return view('admin.auth.login');
}
public function showRegistrationForm()
{
return view('admin.auth.register');
}
it will help you to open another login form for admin
creating a middleware for admin
class RedirectIfNotAdmin
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #param string|null $guard
* #return mixed
*/
public function handle($request, Closure $next, $guard = 'admin')
{
if (!Auth::guard($guard)->check()) {
return redirect('/');
}
return $next($request);
}
}
register middleware in kernel.php
protected $routeMiddleware = [
'admin' => \App\Http\Middleware\RedirectIfNotAdmin::class,
];
use this middleware in AdminController e.g.,
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Requests;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Auth;
class AdminController extends Controller
{
public function __construct(){
$this->middleware('admin');
}
public function index(){
return view('admin.dashboard');
}
}
That's all needed to make it working and also to get json of authenticated admin use
Auth::guard('admin')->user()
Edit - 1
We can access authenticated user directly using
Auth::user() but if you have two authentication table then you have to use
Auth::guard('guard_name')->user()
for logout
Auth::guard('guard_name')->user()->logout()
for authenticated user json
Auth::guard('guard_name')->user()

Related

unable to login as admin in laravel 5.8

I have multi-authentication set up in my laravel app. I am trying to create multiple authentication using default authentication laravel 5.8. I have two tables one is users and other is admins. I have configured the guards for admin. User login works fine, no issues but when I try to login the admin, it doesn't work even if I login with correct credentials. Password field validation works if I use less then 6 character. Please help me to solve this problem.enter code here
My Admin model is
<?php
namespace App;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
class Admin extends Authenticatable {
use Notifiable;
protected $guard = 'admin';
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name', 'email', 'password', 'title',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password', 'remember_token',
];
/**
* The attributes that should be cast to native types.
*
* #var array
*/
protected $casts = [
'email_verified_at' => 'datetime',
];
}
Guard setting is
'guards' => [
'web' => [
'driver' => 'session',
'provider' => 'users',
],
'api' => [
'driver' => 'token',
'provider' => 'users',
'hash' => false,
],
'admin' => [
'driver' => 'session',
'provider' => 'admins',
],
],
'providers' => [
'users' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admins' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
],
// 'users' => [
// 'driver' => 'database',
// 'table' => 'users',
// ],
],
'passwords' => [
'users' => [
'provider' => 'users',
'table' => 'password_resets',
'expire' => 60,
],
'admins' => [
'provider' => 'admins',
'table' => 'password_resets',
'expire' => 60,
],
],
AdminLoginController is
namespace App\Http\Controllers\Auth;
use App\Http\Controllers\Controller;
use Auth;
use Illuminate\Http\Request;
class AdminLoginController extends Controller {
public function __construct() {
$this->middleware('guest:admin')->except('logout');
}
public function showLoginForm() {
return view('auth.admin-login');
}
protected function guard() {
return Auth::guard('admin');
}
public function login(Request $request) {
//validate the form
$this->validate($request, [
'email' => 'required|email',
'password' => 'required|min:6',
]);
//attemp to login
if (Auth::guard('admin')->attempt(['email' => $request->email, 'password' => $request->password], $request->remember)) {
//Authentication passed...
return 'success';
//return redirect()
//->intended(route('admin.dashboardsdsdsd'));
//if login success then redirect to page
// if not success then redirect to back
}
return redirect()->back()->withInput($request->only('email', 'remember'));
}
}
Route is
Route::get('/', function () {
return view('welcome');
});
Auth::routes();
Route::get('/home', 'HomeController#index')->name('home');
Route::get('admin', 'AdminController#index')->name('admin.dashboard');
Route::get('admin/login', 'Auth\AdminLoginController#showLoginForm')->name('admin.login');
Route::post('admin/login', 'Auth\AdminLoginController#login')->name('admin.login.submit');
Please help me to resolve this issue, so that admin can login.
There are two main reasons:
First one: your hash password is not correct, so open this website ( which is MD5 Hash Generator) then put any number that you like, take it and create a new admin account directly from database and paste the password then try
Second one: Clear your cache and view :
php artisan view:clear
php artisan cache:clear

different login routes and login views for student and admin

Every laravel newbie struggles with multi auth, I am no exception
I am trying to make student management system. There will two different routs for admin admin/login and for student student/login.
The student can't register itself, but he will be registered by admin.
So a student has only access to student/dashboard, registration of students will be done by the admin on admin/dashboard.
Below is the detail what I have already done:
created migration for both admin and student.
created guard for both admin and student.
modified login controller and added adminLogin and studentLogin methods.
modified RedirectIfAuthenticated middleware
Config/auth.php
'defaults' => [
'guard' => 'web',
'passwords' => 'users',
],
'guards' => [
'web' => [
'driver' => 'session',
'provider' => 'users',
],
'students' => [
'driver' => 'session',
'provider' => 'students',
],
'web-admin'=>[
'driver'=>'session',
'provider'=>'admin',
],
'api' => [
'driver' => 'token',
'provider' => 'students',
'hash' => false,
],
],
'providers' => [
'students' => [
'driver' => 'eloquent',
'model' => App\Student::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
],
'passwords' => [
'students' => [
'provider' => 'students',
'table' => 'password_resets',
'expire' => 60,
],
'admin' => [
'provider' => 'admin',
'table' => 'password_resets',
'expire' => 60,
],
],
LoginController.php
lass LoginController extends Controller
{
use AuthenticatesUsers;
public function __construct()
{
$this->middleware('guest')->except('logout');
$this->middleware('guest:web-admin')->except('logout');
$this->middleware('guest:students')->except('logout');
}
public function showAdminLoginForm()
{
return view('admin.login', ['url' => 'admin']);
}
public function adminLogin(Request $request)
{
$this->validate($request, [
'admin_id' => 'required',
'password' => 'required|min:8'
]);
if (Auth::guard('admin')->attempt(['admin_id' => $request->adminid, 'password' => $request->password], $request->get('remember'))) {
return redirect()->intended('/admin/dashboard');
}
return back()->withInput($request->only('admin_id', 'remember'));
}
public function showStudentLoginForm()
{
return view('student.login', ['url' => 'student']);
}
public function studentLogin(Request $request)
{
$this->validate($request, [
'roll_no' => 'required',
'password' => 'required|min:8'
]);
if (Auth::guard('writer')->attempt(['roll_no' => $request->roll_no, 'password' => $request->password], $request->get('remember'))) {
return redirect()->intended('/student/dashboard');
}
return back()->withInput($request->only('roll_no', 'remember'));
}
}
RedirectAuthenticated.php
class RedirectIfAuthenticated
{
public function handle($request, Closure $next, $guard = null)
{
if (Auth::guard($guard)->check()) {
if('web_admin'==='$guard'){
return redirect('/admin/dashboard');
}
return redirect('/admin/login');
}
if (Auth::guard($guard)->check()) {
if('students'==='$guard'){
return redirect('/student/dashboard');
}
return redirect('/student/login');
}
return $next($request);
}
}
I have created two folders in the view, student and admin. They both have two files. login.blade.php and dashboard.blade.php
What laravel does it it shows login, and register under auth folder.
I want to give two routes one for /admin/login which return admin.login view.
Same for student /student/login which return student.login view.
I want to remove /register route and make the link to available on admin dashboard , there will be no admin register link.
Also restrict the user from accessing admin area.
**I don't want the whole code, just help me steps and way that I should follow or changes I have to make **
Finally I solved it. I didn't use php artisan make:auth, instead I did it from scratch. Created a fresh project, deleted User.php and the migration.
Created models Student.php and Admin.php along with migrations and controllers.
php artisan make:model Student -mc
php artisan make:model Admin -mc
After than I created guards, I deleted default guard (I don't know It was right to do so, but I felt that if there is no need of default guard and also it was using users table so I deleted).
Here is config/auth.php
'guards' => [
'student'=>[
'driver'=>'session',
'provider'=>'students'
],
'admin'=>[
'driver'=>'session',
'provider'=>'admins'
],
],
'providers' => [
'students'=>[
'driver'=>'eloquent',
'model'=>App\Student::class,
],
'admins'=>[
'driver'=>'eloquent',
'model'=>App\Admin::class,
]
So I have two guards student and admin.
Here is the admin model Admin.php
class Admin extends Authenticatable
{
use Notifiable;
protected $fillable = [
'firstname', 'lastname','admin_id', 'password',
];
protected $hidden = [
'password', 'remember_token',
];
protected $casts = [
'email_verified_at' => 'datetime',
];
}
and model Student Student.php
class Student extends Authenticatable
{
use Notifiable;
protected $fillable = [
'firstname', 'lastname','admin_id', 'password',
];
protected $hidden = [
'password', 'remember_token',
];
protected $casts = [
'email_verified_at' => 'datetime',
];
}
After this I modified AdminController.php
class AdminsController extends Controller
{
use AuthenticatesUsers;
protected $guard = 'admin';
public function showLogin(){
return view('admin.login');
}
public function dashboard(){
return view('admin.dashboard');
}
public function login(Request $request){
$this->validate($request,[
'admin_id' => 'required',
'password'=>'required|min:8',
]);
if(Auth::guard('admin')->attempt(['admin_id'=>$request['admin_id'], 'password'=>$request['password']])){
return redirect('admin/dashboard');
}
return redirect('/admin');
}
}
Then I created routes Web.php
Route::get('/', function () {
return view('welcome');
});
Route::get('/admin','AdminsController#showLogin');
Route::get('/student','StudentsController#showLogin');
Route::get('/admin/dashboard','AdminsController#dashboard');
Route::get('/student','StudentsController#showLogin');
Route::post('/admin/login','AdminsController#login');
Route::post('/student/login','StudentsController#login');
Now, at this time login works. I still need to do a lot. If any suggestion, I welcome that, please comment below.

How to create multi auth in laravel 5.6?

I used to be for laravel 5.5 and earlier than https://github.com/Hesto/multi-auth .
But this repository don't update for laravel 5.6.
How to create multi auth in Laravel 5.6?
After lots of digging and lots of questions & answers I have finally managed to work Laravel 5.6 Multi Auth with two table, So I'm writing Answer of my own Question.
How to implement Multi Auth in Larvel
As Mentioned above.
Two table admin and users
Laravel 5.2 has a new artisan command.
php artisan make:auth
it will generate basic login/register route, view and controller for user table.
Make a admin table as users table for simplicity.
Controller For Admin
app/Http/Controllers/AdminAuth/AuthController
app/Http/Controllers/AdminAuth/PasswordController
(note: I just copied these files from app/Http/Controllers/Auth/AuthController here)
config/auth.php
//Authenticating guards
'guards' => [
'user' =>[
'driver' => 'session',
'provider' => 'user',
],
'admin' => [
'driver' => 'session',
'provider' => 'admin',
],
],
//User Providers
'providers' => [
'user' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
]
],
//Resetting Password
'passwords' => [
'clients' => [
'provider' => 'client',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
'admins' => [
'provider' => 'admin',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
],
route.php
Route::group(['middleware' => ['web']], function () {
//Login Routes...
Route::get('/admin/login','AdminAuth\AuthController#showLoginForm');
Route::post('/admin/login','AdminAuth\AuthController#login');
Route::get('/admin/logout','AdminAuth\AuthController#logout');
// Registration Routes...
Route::get('admin/register', 'AdminAuth\AuthController#showRegistrationForm');
Route::post('admin/register', 'AdminAuth\AuthController#register');
Route::get('/admin', 'AdminController#index');
});
AdminAuth/AuthController.php
Add two methods and specify $redirectTo and $guard
protected $redirectTo = '/admin';
protected $guard = 'admin';
public function showLoginForm()
{
if (view()->exists('auth.authenticate')) {
return view('auth.authenticate');
}
return view('admin.auth.login');
}
public function showRegistrationForm()
{
return view('admin.auth.register');
}
it will help you to open another login form for admin
creating a middleware for admin
class RedirectIfNotAdmin
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #param string|null $guard
* #return mixed
*/
public function handle($request, Closure $next, $guard = 'admin')
{
if (!Auth::guard($guard)->check()) {
return redirect('/');
}
return $next($request);
}
}
register middleware in kernel.php
protected $routeMiddleware = [
'admin' => \App\Http\Middleware\RedirectIfNotAdmin::class,
];
use this middleware in AdminController
e.g.,
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Requests;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Auth;
class AdminController extends Controller
{
public function __construct(){
$this->middleware('admin');
}
public function index(){
return view('admin.dashboard');
}
}
That's all needed to make it working and also to get json of authenticated admin use
Auth::guard('admin')->user()
We can access authenticated user directly using
Auth::user()
but if you have two authentication table then you have to use
Auth::guard('guard_name')->user()
for logout
Auth::guard('guard_name')->user()->logout()
for authenticated user json
Auth::guard('guard_name')->user()

Can Anyone Explain Laravel 5.2 Multi Auth with Example

I am trying to authenticate users and admin form user table and admin table respectively. I am using the User model as provided by laravel out of the box and created the same for Admin. I have added a guard key and provider key into auth.php.
Guards
'guards' => [
'user' =>[
'driver' => 'session',
'provider' => 'user',
],
'admin' => [
'driver' => 'session',
'provider' => 'admin',
],
],
Providers
'providers' => [
'user' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
]
],
Routes
Route::group(['middleware' => ['web']], function () {
// Login Routes.
Route::get('/admin/login','AdminAuth\AuthController#showLoginForm');
Route::post('/admin/login','AdminAuth\AuthController#login');
Route::get('/admin/logout','AdminAuth\AuthController#logout');
// Registration Routes.
Route::get('admin/register', 'AdminAuth\AuthController#showRegistrationForm');
Route::post('admin/register', 'AdminAuth\AuthController#register');
Route::get('/admin', 'AdminController#index');
});
I have created a directory called AuthAdmin where Laravel's default AuthController.php and PasswordController.php files are present. (Namespace Modified accordingly)
First of all, in Laravel's docs mentioned that how to specify custom guard while authenticating like this which isn't working.
There's another method mentioned in Laravel's docs to use a guard which is not working too.
It would be beneficial if someone could resolve the issues and correct me if I am wrong.
After lots of digging and lots of questions & answers I have finally managed to work Laravel 5.2 Multi Auth with two table, So I'm writing Answer of my own Question.
How to implement Multi Auth in Laravel 5.2
As Mentioned above.
Two table admin and users
Laravel 5.2 has a new artisan command.
php artisan make:auth
it will generate basic login/register route, view and controller for user table.
Make a admin table as users table for simplicity.
Controller For Admin
app/Http/Controllers/AdminAuth/AuthController
app/Http/Controllers/AdminAuth/PasswordController
(note: I just copied these files from app/Http/Controllers/Auth/AuthController here)
config/auth.php
//Authenticating guards
'guards' => [
'user' =>[
'driver' => 'session',
'provider' => 'user',
],
'admin' => [
'driver' => 'session',
'provider' => 'admin',
],
],
//User Providers
'providers' => [
'user' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
]
],
//Resetting Password
'passwords' => [
'clients' => [
'provider' => 'client',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
'admins' => [
'provider' => 'admin',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
],
route.php
Route::group(['middleware' => ['web']], function () {
//Login Routes...
Route::get('/admin/login','AdminAuth\AuthController#showLoginForm');
Route::post('/admin/login','AdminAuth\AuthController#login');
Route::get('/admin/logout','AdminAuth\AuthController#logout');
// Registration Routes...
Route::get('admin/register', 'AdminAuth\AuthController#showRegistrationForm');
Route::post('admin/register', 'AdminAuth\AuthController#register');
Route::get('/admin', 'AdminController#index');
});
AdminAuth/AuthController.php
Add two methods and specify $redirectTo and $guard
protected $redirectTo = '/admin';
protected $guard = 'admin';
public function showLoginForm()
{
if (view()->exists('auth.authenticate')) {
return view('auth.authenticate');
}
return view('admin.auth.login');
}
public function showRegistrationForm()
{
return view('admin.auth.register');
}
it will help you to open another login form for admin
creating a middleware for admin
class RedirectIfNotAdmin
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #param string|null $guard
* #return mixed
*/
public function handle($request, Closure $next, $guard = 'admin')
{
if (!Auth::guard($guard)->check()) {
return redirect('/');
}
return $next($request);
}
}
register middleware in kernel.php
protected $routeMiddleware = [
'admin' => \App\Http\Middleware\RedirectIfNotAdmin::class,
];
use this middleware in AdminController
e.g.,
middleware('admin');
}
public function index(){
return view('admin.dashboard');
}
}
That's all needed to make it working and also to get json of authenticated admin use
`Auth::guard('admin')->user()`
**Edit - 1**
We can access authenticated user directly using
`Auth::user()`
but if you have two authentication table then you have to use
Auth::guard('guard_name')->user()
for logout
Auth::guard('guard_name')->user()->logout()
for authenticated user json
Auth::guard('guard_name')->user()
##Edit 2
Now you can download Laravel 5.2 Multiauth implemented Project http://imrealashu.in/code/laravel/multi-auth-with-laravel-5-2-2/
In case this helps anyone, and this may just be due to my lack of understanding of middleware, here's what I had to do to get this working (in addition to the steps taken by #imrealashu)...
In route.php:
Route::get('/admin', [
'middleware' => 'admin',
'uses' => 'AdminController#index'
]);
This is in the web middleware group. Before this I tried putting it in a separate admin middleware group and even in an auth:admin group but this didn't work, it only worked for me when I specified the middleware as admin on the route itself. I have no idea why this is but I hope it saves others from pulling their hair out like I did.
It's very easy in laravel 5.6. Just go to config/auth.php and add this line in providers array:
'admins' => [
'driver' => 'database',
'table' => 'admin_table'
]
Note that we used database for driver not eloquent.
Now add this to guards array:
'admin_guard' => [
'driver' => 'session',
'provider' => 'admins'
]
Now we're done! Use this when working with admins table:
Auth::guard('admin_guard')->User();
Cheers.

How to Create Multi Auth in Laravel 5.2

I have made multi auth but i have problem with final code. I have code like this
php artisan make:auth
it will generate basic login/register route, view and controller for user table.
Make a admin table as users table for simplicity.
Controller For Admin
app/Http/Controllers/AdminAuth/AuthController
app/Http/Controllers/AdminAuth/PasswordController
(note: I just copied these files from app/Http/Controllers/Auth/AuthController here)
config/auth.php
//Authenticating guards
'guards' => [
'user' =>[
'driver' => 'session',
'provider' => 'user',
],
'admin' => [
'driver' => 'session',
'provider' => 'admin',
],
],
//User Providers
'providers' => [
'user' => [
'driver' => 'eloquent',
'model' => App\User::class,
],
'admin' => [
'driver' => 'eloquent',
'model' => App\Admin::class,
]
],
//Resetting Password
'passwords' => [
'clients' => [
'provider' => 'client',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
'admins' => [
'provider' => 'admin',
'email' => 'auth.emails.password',
'table' => 'password_resets',
'expire' => 60,
],
],
route.php
Route::group(['middleware' => ['web']], function () {
//Login Routes...
Route::get('/admin/login','AdminAuth\AuthController#showLoginForm');
Route::post('/admin/login','AdminAuth\AuthController#login');
Route::get('/admin/logout','AdminAuth\AuthController#logout');
// Registration Routes...
Route::get('admin/register', 'AdminAuth\AuthController#showRegistrationForm');
Route::post('admin/register', 'AdminAuth\AuthController#register');
Route::get('/admin', 'AdminController#index');
});
AdminAuth/AuthController.php
Add two methods and specify $redirectTo and $guard
protected $redirectTo = '/admin';
protected $guard = 'admin';
public function showLoginForm()
{
if (view()->exists('auth.authenticate')) {
return view('auth.authenticate');
}
return view('admin.auth.login');
}
public function showRegistrationForm()
{
return view('admin.auth.register');
}
it will help you to open another login form for admin
creating a middleware for admin
class RedirectIfNotAdmin
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #param string|null $guard
* #return mixed
*/
public function handle($request, Closure $next, $guard = 'admin')
{
if (!Auth::guard($guard)->check()) {
return redirect('/');
}
return $next($request);
}
}
register middleware in kernel.php
protected $routeMiddleware = [
'admin' => \App\Http\Middleware\RedirectIfNotAdmin::class,
];
use this middleware in AdminController e.g.,
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Http\Requests;
use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Auth;
class AdminController extends Controller
{
public function __construct(){
$this->middleware('admin');
}
public function index(){
return view('admin.dashboard');
}
}
And what does this code mean Auth::guard('admin')->user() ? And where must i type that code?
And what does this code mean Auth::guard('admin')->user() ?
In simple word, Auth::guard('admin')->user() is used when you need to get details of logged in user. But, in multi auth system, there can be two logged in users (admin/client). So you need to specify that which user you want to get. So by guard('admin'), you tell to get user from admin table.
Where must i type that code?
As from answer, you can understand that where must you use it. But still I can explain with example. Suppose there are multiple admins. Each can approve users request (like post/comments etc). So when an admin approve any request, then to insert id of that admin into approved_by column of post, you must use this line.

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