UserGroupBackendForm: Fix that autosubmit do not have any effect

refs #7343

application/forms/Config/UserGroup/UserGroupBackendForm.php

@@ -13,6 +13,13 @@ use Icinga\Forms\ConfigForm;
  */
 class UserGroupBackendForm extends ConfigForm
 {
+    /**
+     * The backend to load when displaying the form for the first time
+     *
+     * @var string
+     */
+    protected $backendToLoad;
+
     /**
      * Initialize this form
      */
@@ -53,10 +60,7 @@ class UserGroupBackendForm extends ConfigForm
             throw new NotFoundError('No user group backend called "%s" found', $name);
         }
 
-        $data = $this->config->getSection($name)->toArray();
+        $this->backendToLoad = $name;
-        $data['type'] = $data['backend'];
-        $data['name'] = $name;
-        $this->populate($data);
         return $this;
     }
 
@@ -187,7 +191,8 @@ class UserGroupBackendForm extends ConfigForm
                 'autosubmit'        => true,
                 'label'             => $this->translate('Backend Type'),
                 'description'       => $this->translate('The type of this user group backend'),
-                'multiOptions'      => $backendTypes
+                'multiOptions'      => $backendTypes,
+                'value'             => $backendType
             )
         );
 
@@ -195,4 +200,17 @@ class UserGroupBackendForm extends ConfigForm
         $backendForm->createElements($formData);
         $this->addElements($backendForm->getElements());
     }
+
+    /**
+     * Populate the configuration of the backend to load
+     */
+    public function onRequest()
+    {
+        if ($this->backendToLoad) {
+            $data = $this->config->getSection($this->backendToLoad)->toArray();
+            $data['type'] = $data['backend'];
+            $data['name'] = $this->backendToLoad;
+            $this->populate($data);
+        }
+    }
 }