ldc-legaulois/app/Http/Requests/SendMessageRequest.php

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Support\Facades\Auth;

class SendMessageRequest extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return boolean
     */
    public function authorize()
    {
        return Auth::guard('customer')->check();
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'message' => 'required|string|max:255|min:10',
            'to' => 'required|exists:customers,username'
        ];
    }
}