It's implemented using the laravel form request feature which can be implemented with php artisan:make request command. The code within the rules function checks for validation issues.

StoreBlogPostRequest

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;

class StoreBlogPostRequest extends FormRequest {

    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize() {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules() {
        return [
            'title' => 'bail|required|max:255|unique:posts,title',
            'description' => 'required|max:255',
            'content' => 'required',
        ];
    }

}