Fix exception when using dictionary on host

patch.patch

diff --git a/application/controllers/DataController.php b/application/controllers/DataController.php
index ae4bbcf3..588c4604 100644
--- a/application/controllers/DataController.php
+++ b/application/controllers/DataController.php
@@ -6,7 +6,7 @@ use gipfl\Web\Widget\Hint;
 use Icinga\Exception\NotFoundError;
 use Icinga\Module\Director\Forms\DirectorDatalistEntryForm;
 use Icinga\Module\Director\Forms\DirectorDatalistForm;
-use Icinga\Module\Director\Forms\IcingaServiceDictionaryMemberForm;
+use Icinga\Module\Director\Forms\IcingaDictionaryMemberForm;
 use Icinga\Module\Director\Objects\DirectorDatalist;
 use Icinga\Module\Director\Objects\IcingaHost;
 use Icinga\Module\Director\Objects\IcingaObject;
@@ -193,7 +193,8 @@ class DataController extends ActionController
             'object_name' => $field->getSetting('template_name')
         ], $connection);

-        $form = new IcingaServiceDictionaryMemberForm();
+        $form = new IcingaDictionaryMemberForm();
+        $form->setType(get_class($object));
         $form->setDb($connection);
         if ($instance) {
             $instanceObject = $object::create([
diff --git a/application/forms/IcingaServiceDictionaryMemberForm.php b/application/forms/IcingaDictionaryMemberForm.php
similarity index 78%
rename from application/forms/IcingaServiceDictionaryMemberForm.php
rename to application/forms/IcingaDictionaryMemberForm.php
index 90b8f94b..8715b24c 100644
--- a/application/forms/IcingaServiceDictionaryMemberForm.php
+++ b/application/forms/IcingaDictionaryMemberForm.php
@@ -4,14 +4,17 @@ namespace Icinga\Module\Director\Forms;

 use Icinga\Module\Director\Web\Form\DirectorObjectForm;
 use Icinga\Module\Director\Objects\IcingaService;
+use Icinga\Module\Director\Objects\IcingaHost;

-class IcingaServiceDictionaryMemberForm extends DirectorObjectForm
+class IcingaDictionaryMemberForm extends DirectorObjectForm
 {
-    /** @var IcingaService */
+    /** @var IcingaObject */
     protected $object;

     private $succeeded;

+    protected $object_class;
+
     /**
      * @throws \Zend_Form_Exception
      */
@@ -28,18 +31,23 @@ class IcingaServiceDictionaryMemberForm extends DirectorObjectForm
         $this->groupMainProperties()->setButtons();
     }

+    public function setType($object_class) {
+           $this->object_class = $object_class;
+    }
+
     protected function isNew()
     {
         return $this->object === null;
     }

+
     protected function deleteObject($object)
     {
     }

     protected function getObjectClassname()
     {
-        return IcingaService::class;
+        return $this->object_class;
     }

     public function succeeded()