Cakephp 3 : Dynamic Validation Rules

controller.php

<?php
class UsersController extends AppController
{
  $user->type = "order";
  /* Success save */
  if($this->Users->save($user))
  {
  }
  /* Failed save */
  else
  {
  }
}

model.php

<?php
class Users extends Table
{
  public function buildRules(RulesChecker $rules)
    {
        $check = function(user){
            if($user->type == "order")
            {
                return false;
            }
            else
            {
                return true;
            }
        };
        if($check)
            $rules->add($rules->isUnique(['email' , 'prospect_groups_id']));
        return $rules;
    }
}
?>

model2.php

<?php
class Users extends Table
{
  public function buildRules(RulesChecker $rules)
    {
        $check = function($user) {
            return $user->price < 100 && $user->shipping_mode === 'free';
        };
        $rules->add($check, [
            'errorField' => 'shipping_mode',
            'message' => 'No free shipping for orders under 100!'
        ]);
        return $rules;
    }
}
?>