laravel exits message code example

Example 1: how to add an custom error to validater error in laravel

if (request('event') == null) {
    $validator->errors()->add('event', 'Please select an event');
}

Example 2: laravel validation

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Facades\Validator;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }

    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        Validator::extend('foo', function ($attribute, $value, $parameters, $validator) {
            return $value == 'foo';
        });
    }
}