在MVC模式中转换表单数据的最佳位置

Question

Let's say that model insert data to database.

class Model
{
    public function insert($value) {
        // putting $value to database to integer field
    }

}

I want to convert $value to int by (int) $value to prevent the insertion of the non-numeric value.

Where should I do this? In model method or in controller?

class Controller
{
    public function indexAction() {
        $model = new Model;
        $model->insert($_POST['user_id']);
    }
}

Answer 1

1. It hardly makes any difference to PHP whether a value is a numeric string or an integer, it'll just work with it the same way and convert implicitly when actually necessary.
2. If this is actually a concern though, the controller is logically the right place to do it. Numbers being numeric strings instead of integers is a problem unique to the method of input, and a controller is an "input adapter" if you will which takes input in a specific form and passes it through to the model in a standardised format.