Create a generic method for generating slugs that are unique to the table.

Ticket #20

src/Hackspace/Bundle/CalciferBundle/Entity/BaseEntity.php

@@ -9,7 +9,9 @@
 namespace Hackspace\Bundle\CalciferBundle\Entity;
 
 use Doctrine\ORM\Mapping as ORM;
-use Doctrine\ORM\PersistentCollection;
+use Doctrine\ORM\EntityManager;
+use Doctrine\ORM\EntityRepository;
+use Symfony\Component\Security\Acl\Exception\Exception;
 
 /**
  * A baseclass for all other entities
@@ -60,4 +62,31 @@ abstract class BaseEntity {
             throw new \Exception("Property {$name} does not Exists");
         }
     }
+
+    public function generateSlug($name,EntityManager $em) {
+        $slug = \URLify::filter($name, 255, 'de');
+
+        /** @var EntityRepository $repo */
+        $repo = $em->getRepository(get_class($this));
+
+        $entity = $repo->findOneBy(['slug' => $slug]);
+
+        if (is_null($entity)) {
+            return $slug;
+        } else {
+            $counter = 1;
+            while (true) {
+                $new_slug = $slug . '-' . $counter;
+                $entity = $repo->findOneBy(['slug' => $new_slug]);
+                if (is_null($entity)) {
+                    return $new_slug;
+                }
+                if ($counter === 100) {
+                    throw new \Exception('There are 100 events with the same name, pick a fresh one!');
+                }
+                $counter++;
+            }
+        }
+        return null;
+    }
 }