Custom Validation Rule in Laravel Framework

Download and install the latest version of Composer from https://getcomposer.org/download/
Open Windows Terminal in Visual Studio Code install Laravel Installer with command as below:
```
composer global require laravel/installer
```
Create new folder named LearnLaravelWithRealApps. Use Visual Studio Code open to LearnLaravelWithRealApps foler. In this folder, create new project named LearnLaravelWithRealApps with command as below:
```
laravel new LearnLaravelWithRealApps
```
Run LearnLaravelWithRealApps project with command as below:
```
php artisan serve
```
Open LearnLaravelWithRealApps project with url as below:
```
http://localhost:8000
```

Create new folder named Rules in app folder. Create new PHP file named UsernameRule.php in app/Rules folder as below:

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class UsernameRule implements Rule
{
	public function __construct()
	{
	}

	public function passes($attribute, $value)
	{
		return 'abc' !== $value;
	}

	public function message()
	{
		return 'Username Exists';
	}
}

Create new PHP file named DemoController.php in app/Http/Controllers folder as below:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\Rules\UsernameRule;

class DemoController extends Controller
{
	public function index()
	{
		return view('demo/index');
	}

	public function save(Request $request)
	{
		$this->validate($request, [
			'username' => [
				'required',
				'min:3',
				'max:8',
				new UsernameRule(),
			]
		]);
		return view('demo/success');
	}
}

Create new folder named demo in resources/views folder. In demo folder, create new views as below:

Create new PHP file named index.blade.php in resources/views/demo as below:

<html>

	<head>
		<title>Laravel</title>
	</head>

	<body>

		<h3>Register</h3>
		@if (count($errors) > 0)
		<div class="alert alert-danger">
			<ul>
				@foreach ($errors->all() as $error)
				<li>{{ $error }}</li>
				@endforeach
			</ul>
		</div>
		@endif
		<form method="post" action="{{url('/demo/save')}}">
			@csrf
			<table border="0">
				<tr>
					<td>Username</td>
					<td><input type="text" name="username" value="{{ old('username') }}"></td>
					<td>
						{!! $errors->first('username', '<p class="help-block">:message</p>') !!}
					</td>
				</tr>
				<tr>
					<td>&nbsp;</td>
					<td><input type="submit" value="Save"></td>
				</tr>
			</table>
			
		</form>

	</body>

</html>

Create new PHP file named success.blade.php in resources/views/demo as below:

<html>

	<head>
		<title>Laravel</title>
	</head>

	<body>

		Success

	</body>

</html>

Open web.php file in routes folder, add new routes as below:

<?php
				
use Illuminate\Support\Facades\Route;

use App\Http\Controllers\DemoController;

Route::group([], function () {
	Route::get('/', [DemoController::class, 'index']);
	Route::get('/demo', [DemoController::class, 'index']);
	Route::get('/demo/index', [DemoController::class, 'index']);
	Route::post('/demo/save', [DemoController::class, 'save']);
});

Access index action in Demo controller with following url: http://localhost:8000/demo/index

Output

Click Save button submit form to Save action in Demo controller with invalid data as below:

Click Save button submit form to Save action in Demo controller with valid data

Output

Install Laravel

Custom Validation

Controllers

Views

Demo Views

Index View

Welcome View

Routes

Structure of Laravel Project

Run Application