ldc-mesbr-app/app/Models/Customers.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Customers extends Model
{

    protected $primaryKey = 'hashcode';
    protected $keyType = 'string';

    protected $fillable = ['hashcode', 'email', 'country'];

    protected static function booted()
    {
        static::creating(function ($customer) {
            $customer->country = (new Customers())->getIsoCountry($customer->country);
        });

        static::updating(function ($customer) {
            $customer->country = (new Customers())->getIsoCountry($customer->country);
        });
    }

    private function getIsoCountry($country)
    {
        $country = trim(ucfirst(strtolower($country)));
        switch ($country) {
            case 'Belgique':
                return 56;
            break;
            case 'Luxembourg':
                return 442;
            break;
            default:
                return 250; //France
        }
    }
}