Added NotReferenced validator. (#2)

* Added NotReferenced validator.

Resources/config.xml

@@ -41,5 +41,10 @@
             <argument type="service" id="doctrine" />
             <tag name="validator.constraint_validator" alias="vanio_domain.validator.unique" />
         </service>
+
+        <service id="vanio_domain.validator.not_referenced" class="Vanio\DomainBundle\Validator\NotReferencedValidator">
+            <argument type="service" id="doctrine" />
+            <tag name="validator.constraint_validator" alias="vanio_domain.validator.not_referenced" />
+        </service>
     </services>
 </container>

Validator/NotReferenced.php

@@ -0,0 +1,44 @@
+<?php
+namespace Vanio\DomainBundle\Validator;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * @Annotation
+ */
+class NotReferenced extends Constraint
+{
+    const IS_REFERENCED_ERROR = '0d52565f-bc0f-41ee-9261-4dc68d29548c';
+
+    /** @var array */
+    protected static $errorNames = [
+        self::IS_REFERENCED_ERROR => 'IS_REFERENCED_ERROR',
+    ];
+
+    /** @var string */
+    public $field;
+
+    /** @var string */
+    public $relatedEntity;
+
+    /** @var string|null */
+    public $relatedField = null;
+
+    /** @var string */
+    public $message = 'The entity is referenced by another entity.';
+
+    public function getRequiredOptions(): array
+    {
+        return [ 'field', 'relatedEntity' ];
+    }
+
+    public function getTargets(): string
+    {
+        return self::CLASS_CONSTRAINT;
+    }
+
+    public function validatedBy(): string
+    {
+        return 'vanio_domain.validator.not_referenced';
+    }
+}

Validator/NotReferencedValidator.php

@@ -0,0 +1,58 @@
+<?php
+namespace Vanio\DomainBundle\Validator;
+
+use Doctrine\Common\Persistence\ManagerRegistry;
+use Symfony\Component\PropertyAccess\PropertyAccess;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\ConstraintDefinitionException;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+
+class NotReferencedValidator extends ConstraintValidator
+{
+    /** @var ManagerRegistry */
+    private $registry;
+
+    public function __construct(ManagerRegistry $registry)
+    {
+        $this->registry = $registry;
+    }
+
+    /**
+     * @param mixed $object
+     * @param Constraint $constraint
+     */
+    public function validate($object, Constraint $constraint)
+    {
+        if (!$constraint instanceof NotReferenced) {
+            throw new UnexpectedTypeException($constraint, __NAMESPACE__ . '\Unique');
+        }
+
+        $em = $this->registry->getManagerForClass($constraint->relatedEntity);
+        if (!$em) {
+            throw new ConstraintDefinitionException(sprintf('Unable to find the object manager associated with an entity of class "%s".', $constraint->relatedEntity));
+        }
+        $repository = $em->getRepository($constraint->relatedEntity);
+
+        $accessor = PropertyAccess::createPropertyAccessor();
+        $relatedField = $constraint->relatedField ? $constraint->relatedField : $constraint->field;
+        $relatedValue = $accessor->getValue($object, $constraint->field);
+
+        if (is_callable([ $repository, 'existsBy' ])) {
+            $result = $repository->existsBy([
+                $relatedField => $relatedValue,
+            ]);
+        }
+        else {
+            $result = $repository->findBy([
+                $relatedField => $relatedValue,
+            ]);
+        }
+
+        if ($result) {
+            $this->context->buildViolation($constraint->message)
+                ->setCode(NotReferenced::IS_REFERENCED_ERROR)
+                ->addViolation();
+        }
+    }
+}

Validator/UniqueValidator.php

@@ -55,7 +55,6 @@ public function validate($object, Constraint $constraint)
             return;
         }
 
-
         $id = $constraint->id;
         if (!is_null($id) && count($result) === 1 &&
             $em->getReference($constraint->class, $accessor->getValue($object, $id)) === current($result)) {