public function testToAndFromString()
 {
     $this->custom->setText('value');
     $this->assertTrue($this->custom->getText() == 'value');
     $this->custom->setColumnName('column_name');
     $this->assertTrue($this->custom->getColumnName() == 'column_name');
     $newCustom = new Zend_Gdata_Spreadsheets_Extension_Custom();
     $doc = new DOMDocument();
     $doc->loadXML($this->custom->saveXML());
     $newCustom->transferFromDom($doc->documentElement);
     $this->assertTrue($this->custom->getText() == $newCustom->getText());
     $this->assertTrue($this->custom->getColumnName() == $newCustom->getColumnName());
 }

 protected function takeChildFromDOM($child)
 {
     switch ($child->namespaceURI) {
         case $this->lookupNamespace('gsx'):
             $custom = new Zend_Gdata_Spreadsheets_Extension_Custom($child->localName);
             $custom->transferFromDOM($child);
             $this->addCustom($custom);
             break;
         default:
             parent::takeChildFromDOM($child);
             break;
     }
 }

 /**
  * Add an individual custom row element to this list entry.
  * @param Zend_Gdata_Spreadsheets_Extension_Custom $custom The custom
  *             element to be added.
  * @return Zend_Gdata_Spreadsheets_ListEntry Provides a fluent interface.
  */
 public function addCustom($custom)
 {
     $this->_custom[] = $custom;
     $this->_customByName[$custom->getColumnName()] = $custom;
     return $this;
 }

 /**
  * Updates an existing row with provided data.
  *
  * @param ListEntry $entry The row entry to update
  * @param array $newRowData An array of column header to row data
  */
 public function updateRow($entry, $newRowData)
 {
     $newCustomArr = array();
     foreach ($newRowData as $k => $v) {
         $newCustom = new Zend_Gdata_Spreadsheets_Extension_Custom();
         $newCustom->setText($v)->setColumnName($k);
         $newCustomArr[] = $newCustom;
     }
     $entry->setCustom($newCustomArr);
     return $entry->save();
 }