ImportSourceSql: cache query column list

fixes #1071

application/forms/ImportSourceForm.php

@@ -63,6 +63,18 @@ class ImportSourceForm extends DirectorObjectForm
         }
     }
 
+    public function hasChangedSetting($name)
+    {
+        if ($this->hasBeenSent() && $this->hasObject()) {
+            /** @var ImportSource $object */
+            $object = $this->getObject();
+            return $object->getStoredSetting($name)
+                !== $this->getSentValue($name);
+        } else {
+            return false;
+        }
+    }
+
     protected function addSettings()
     {
         if (! ($class = $this->getProviderClass())) {

library/Director/Data/Db/DbObjectWithSettings.php

@@ -56,6 +56,16 @@ abstract class DbObjectWithSettings extends DbObject
         return $default;
     }
 
+    public function getStoredSetting($name, $default = null)
+    {
+        $stored = $this->fetchSettingsFromDb();
+        if (array_key_exists($name, $stored)) {
+            return $stored[$name];
+        }
+
+        return $default;
+    }
+
     public function __unset($key)
     {
         if ($this->hasProperty($key)) {

library/Director/Import/ImportSourceSql.php

@@ -3,9 +3,13 @@
 namespace Icinga\Module\Director\Import;
 
 use Icinga\Data\Db\DbConnection;
+use Icinga\Module\Director\Forms\ImportSourceForm;
 use Icinga\Module\Director\Hook\ImportSourceHook;
+use Icinga\Module\Director\Objects\ImportSource;
 use Icinga\Module\Director\Util;
+use Icinga\Module\Director\Web\Form\Filter\QueryColumnsFromSql;
 use Icinga\Module\Director\Web\Form\QuickForm;
+use ipl\Html\Html;
 
 class ImportSourceSql extends ImportSourceHook
 {
@@ -18,17 +22,43 @@ class ImportSourceSql extends ImportSourceHook
 
     public function listColumns()
     {
+        if ($columns = $this->getSetting('column_cache')) {
+            return explode(', ', $columns);
+        } else {
             return array_keys((array) current($this->fetchData()));
         }
+    }
 
     public static function addSettingsFormFields(QuickForm $form)
     {
+        /** @var ImportSourceForm $form */
         Util::addDbResourceFormElement($form, 'resource');
-        $form->addElement('textarea', 'query', array(
-            'label'    => 'DB Query',
+        /** @var ImportSource $current */
+        $current = $form->getObject();
+
+        $form->addElement('textarea', 'query', [
+            'label'    => $form->translate('DB Query'),
             'required' => true,
             'rows'     => 15,
+        ]);
+        $form->addElement('hidden', 'column_cache', [
+            'value'    => '',
+            'filters'  => [new QueryColumnsFromSql($form)],
+            'required' => true
+        ]);
+        if ($current) {
+            if ($columns = $current->getSetting('column_cache')) {
+                $form->addHtmlHint('Columns: ' . $columns);
+            } else {
+                $form->addHtmlHint(Html::tag(
+                    'p',
+                    ['class' => 'warning'],
+                    $form->translate(
+                        'Please click "Store" once again to determine query columns'
+                    )
                 ));
+            }
+        }
         return $form;
     }
 

library/Director/Web/Form/Filter/QueryColumnsFromSql.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Icinga\Module\Director\Web\Form\Filter;
+
+use Exception;
+use Icinga\Module\Director\Forms\ImportSourceForm;
+use Zend_Filter_Interface;
+
+class QueryColumnsFromSql implements Zend_Filter_Interface
+{
+    /** @var ImportSourceForm */
+    private $form;
+
+    public function __construct(ImportSourceForm $form)
+    {
+        $this->form = $form;
+    }
+
+    public function filter($value)
+    {
+        $form = $this->form;
+        if (empty($value) || $form->hasChangedSetting('query')) {
+            try {
+                return implode(
+                    ', ',
+                    $this->getQueryColumns($form->getSentOrObjectSetting('query'))
+                );
+            } catch (Exception $e) {
+                $this->form->addUniqueException($e);
+                return '';
+            }
+        } else {
+            return $value;
+        }
+    }
+
+    protected function getQueryColumns($query)
+    {
+        return array_keys((array) current(
+            $this->form->getDb()->getDbAdapter()->fetchAll($query)
+        ));
+    }
+}