Symfony widget name format

what is the symfony widget name format and how is it used? / what is it used for? Here is my symfony form with multiple widgets. I have to set the name format so that I can use the widgets in the view.

class EmployeeTaskForm extends BaseForm
{
    private $employeeTaskService;
    private $employeeTask;
    private $empNumber;

    public function configure()
    {
        $empNumber = $this->getOption('empNumber');
        $this->empNumber = $empNumber;
        $employeeTasks = $this->getOption('employeeTasks');

        // Note: Widget names were kept from old non-symfony version
        $widgets = array('empNumber' => new sfWidgetFormInputHidden(array(), array('value' => $empNumber)));
        $validators = array('empNumber' => new sfValidatorString(array('required' => true)));

        $EmployeeTaskwidgets = $this->getTaskManagerWidgets();
        $labels = $this->getFormLabels();
        $EmployeeTaskvalidators = $this->getTaskManagerValidators();

        $widgets = array_merge($widgets, $EmployeeTaskwidgets);
        $validators = array_merge($validators, $EmployeeTaskvalidators);

        $this->setWidgets($widgets);
        $this->getWidgetSchema()->setLabel($labels);
        $this->setValidators($validators);

        $this->widgetSchema->setNameFormat('employeeTask[%s]');
    }

    /*
     * This fuction will return the widgets of the form
     */
    public function getTaskManagerWidgets(){
        $widgets = array();

        //creating widgets
        $widgets['seqNo'] = new sfWidgetFormInputHidden();
        $widgets['task_name'] = new sfWidgetFormInputText();
        $widgets['description'] = new sfWidgetFormTextarea();
        $widgets['due_date'] = new ohrmWidgetDatePicker(array(), array('id' => 'taskDueDate'));

        return $widgets;
    }


    /*
     * This fuction will return the form validators
     */
    public function getTaskManagerValidators(){
        $validators = array(
            'seqNo' => new sfValidatorNumber(array('required' => false, 'min' => 1)),
            'task_name' => new sfValidatorString(array('required' => true)),
            'description' => new sfValidatorString(array('required' => false)),
            'due_date' => new sfValidatorDate(array('required' => false))

        );

        return $validators;
    }
    /**
     *
     * @return array
     */
    protected function getFormLabels() {
        $labels = array(
            'task_name' => __('Name'),
            'description' => __('Description'),
            'due_date' => __('Due date')

        );

        return $labels;
    }


    public function getEmployeeTask(){
        if (!$this->employeeTask instanceof EmployeeTask) {
            $posts = $this->getValues();
            $employeeTask = new EmployeeTask();
            $employeeTask->task_name = $posts['task_name'];
            $employeeTask->description = $posts['description'];
            $employeeTask->due_date = $posts['due_date'];
            $employeeTask->seqno = $posts['seqNo'];

            $empNumber = $this->getOption('empNumber');
            $seqNo = $this->getOption('seqNo');

            if (empty($seqNo)) {
                $q = Doctrine_Query::create()
                    ->select('MAX(et.seqno)')
                    ->from('EmployeeTask et')
                    ->where('et.emp_number = ?', $empNumber);
                $result = $q->execute(array(), Doctrine::HYDRATE_ARRAY);

                if (count($result) != 1) {
                    throw new PIMServiceException('MAX(seqno) failed.');
                }
                $seqNo = is_null($result[0]['MAX']) ? 1 : $result[0]['MAX'] + 1;

            } else {
                $employeeTask = Doctrine::getTable('EmployeeTask')->find(array('emp_number' => $empNumber,
                    'seqno' => $seqNo));

                if ($employeeTask == false) {
                    throw new PIMServiceException('Invalid employee Task');
                }
            }

            if ($employeeTask === false) {
                $employeeTask = new EmployeeTask();
                $employeeTask->emp_number = $empNumber;
                $employeeTask->seqno = $seqNo;
            }

            $employeeTask->seqno = $seqNo;

            $this->employeeTask = $employeeTask;
        }
        return $this->employeeTask;
    }

    public function save($empNumber){
        $post = $this->getValues();
        $employeeTask = $this->getEmployeeTask();
        $employeeTask->emp_number = $empNumber;

        $employeeTaskService = $this->getEmployeeTaskService();
        $employeeTaskService->saveEmployeeTask($employeeTask);

    }

}

      

        
        
        
      

    

Problem . When I include the line $this->widgetSchema->setNameFormat('employeeTask[%s]');

, I get the errorUnexpected extra form field named "employeeTaskUpdate"

Can someone explain the use of the name format and the correct way to use it?