Properly handle undefined configuration values

fixes #10597

application/forms/Config/GeneralConfigForm.php

@@ -6,7 +6,6 @@ namespace Icinga\Forms\Config;
 use Icinga\Forms\Config\General\ApplicationConfigForm;
 use Icinga\Forms\Config\General\LoggingConfigForm;
 use Icinga\Forms\ConfigForm;
-use Icinga\Web\Notification;
 
 /**
  * Form class for application-wide and logging specific settings
@@ -32,43 +31,4 @@ class GeneralConfigForm extends ConfigForm
         $this->addElements($appConfigForm->createElements($formData)->getElements());
         $this->addElements($loggingConfigForm->createElements($formData)->getElements());
     }
-
-    /**
-     * @see Form::onSuccess()
-     */
-    public function onSuccess()
-    {
-        $sections = array();
-        foreach ($this->getValues() as $sectionAndPropertyName => $value) {
-            list($section, $property) = explode('_', $sectionAndPropertyName, 2);
-            if (! isset($sections[$section])) {
-                $sections[$section] = array();
-            }
-            $sections[$section][$property] = $value;
-        }
-        foreach ($sections as $section => $config) {
-            $this->config->setSection($section, $config);
-        }
-
-        if ($this->save()) {
-            Notification::success($this->translate('New configuration has successfully been stored'));
-        } else {
-            return false;
-        }
-    }
-
-    /**
-     * @see Form::onRequest()
-     */
-    public function onRequest()
-    {
-        $values = array();
-        foreach ($this->config as $section => $properties) {
-            foreach ($properties as $name => $value) {
-                $values[$section . '_' . $name] = $value;
-            }
-        }
-
-        $this->populate($values);
-    }
 }

application/forms/Config/ResourceConfigForm.php

@@ -163,10 +163,10 @@ class ResourceConfigForm extends ConfigForm
                         return false;
                     }
                 }
-                $this->add($this->getValues());
+                $this->add(array_filter($this->getValues()));
                 $message = $this->translate('Resource "%s" has been successfully created');
             } else { // edit existing resource
-                $this->edit($resource, $this->getValues());
+                $this->edit($resource, array_filter($this->getValues()));
                 $message = $this->translate('Resource "%s" has been successfully changed');
             }
         } catch (InvalidArgumentException $e) {

application/forms/ConfigForm.php

@@ -6,6 +6,7 @@ namespace Icinga\Forms;
 use Exception;
 use Zend_Form_Decorator_Abstract;
 use Icinga\Web\Form;
+use Icinga\Web\Notification;
 use Icinga\Application\Config;
 
 /**
@@ -33,6 +34,47 @@ class ConfigForm extends Form
         return $this;
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function onSuccess()
+    {
+        $sections = array();
+        foreach ($this->getValues() as $sectionAndPropertyName => $value) {
+            if ($value === '') {
+                $value = null; // Causes the config writer to unset it
+            }
+
+            list($section, $property) = explode('_', $sectionAndPropertyName, 2);
+            $sections[$section][$property] = $value;
+        }
+
+        foreach ($sections as $section => $config) {
+            $this->config->setSection($section, $config);
+        }
+
+        if ($this->save()) {
+            Notification::success($this->translate('New configuration has successfully been stored'));
+        } else {
+            return false;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function onRequest()
+    {
+        $values = array();
+        foreach ($this->config as $section => $properties) {
+            foreach ($properties as $name => $value) {
+                $values[$section . '_' . $name] = $value;
+            }
+        }
+
+        $this->populate($values);
+    }
+
     /**
      * Persist the current configuration to disk
      *

library/Icinga/Data/Db/DbConnection.php

@@ -130,7 +130,7 @@ class DbConnection implements Selectable, Extensible, Updatable, Reducible, Insp
             'username'          => $this->config->username,
             'password'          => $this->config->password,
             'dbname'            => $this->config->dbname,
-            'charset'           => $this->config->charset,
+            'charset'           => $this->config->charset ?: null,
             'persistent'        => (bool) $this->config->get('persistent', false),
             'options'           => & $genericAdapterOptions,
             'driver_options'    => & $driverOptions