igfs/app/controllers/Users.php

<?php
namespace Controllers;
use Models\User;
use Models\Question;

class Users {
    public function actionCreateUser($username, $email, $password)
    {
        return User::create(['username'=>$username,'email'=>$email,'password'=>$password]);
    }

    public function actionQuestionCount($user_id)
    {
        return Question::where('user_id', $user_id)->count();
    }
}