verify if an email already exists in newsletter table

core/lib/Thelia/Form/NewsletterForm.php

@@ -23,9 +23,12 @@
 
 namespace Thelia\Form;
 
+use Symfony\Component\Validator\Constraints\Callback;
 use Symfony\Component\Validator\Constraints\Email;
 use Symfony\Component\Validator\Constraints\NotBlank;
+use Symfony\Component\Validator\ExecutionContextInterface;
 use Thelia\Core\Translation\Translator;
+use Thelia\Model\NewsletterQuery;
 
 
 /**
@@ -62,7 +65,13 @@ class NewsletterForm extends BaseForm
             ->add('email', 'email', array(
                 'constraints' => array(
                     new NotBlank(),
-                    new Email()
+                    new Email(),
+                    new Callback(array(
+                        "methods" => array(
+                            array($this,
+                                "verifyExistingEmail")
+                        )
+                    ))
                 ),
                 'label' => Translator::getInstance()->trans('email'),
                 'label_attr' => array(
@@ -71,6 +80,14 @@ class NewsletterForm extends BaseForm
             ));
     }
 
+    public function verifyExistingEmail($value, ExecutionContextInterface $context)
+    {
+        $customer = NewsletterQuery::create()->findOneByEmail($value);
+        if ($customer) {
+            $context->addViolation("This email already exists");
+        }
+    }
+
     /**
      * @return string the name of you form. This name must be unique
      */