gistfile1.php

<?php

public function validationProfile(Validator $validator)
    {
        $validator
                >requirePresence('username')
                ->notEmpty('username')
                ->add('username', [
                    'uniqueEmail' => [
                        'rule' => ['validateUnique', [/*'scope' => 'site_id'*/]],
                        'provider' => 'table',
                        'message'  => 'Email già registrata!',
                        'on' => function ($context) {
                            return (empty($context['data']['_username'])) || ($context['data']['username'] !== $context['data']['_username']);
                        }                        
                    ],
                    'emailFormat' => [
                        'rule'    => 'email',
                        'message' => 'Formato email non valido',
                    ]
                ])
                
                ->requirePresence('username_repeat')                
                ->notEmpty('username_repeat', 'Campo obbligatorio')
                ->add('username_repeat', 'usernameRepeat', [
                    'rule'    => ['compareWith', 'username'],
                    'message' => 'L\'email non coincide',
                    'on' => function ($context) {
                        return (empty($context['data']['_username'])) || ($context['data']['username'] !== $context['data']['_username']);
                    }                         
                ])      
                    
                ->notEmpty('password_repeat', 'Campo obbligatorio')
                ->add('password', 'passwordLength', [
                    'rule'    => ['minLength', 3],
                    'message' => 'Campo obbligatorio',
                ])
        
                ->notEmpty('password_repeat', 'Campo obbligatorio')
                ->add('password_repeat', 'passwordRepeat', [
                    'rule'    => ['compareWith', 'password'],
                    'message' => 'La password non coincide',
                ]);                         
                                    
                    
        return $validator;        
    }