gistfile1.php

<?php
public function configure()
  {
      // not really useful, but just in case!
      parent::configure();
      $this->postConfigure();
  }

  public function postConfigure()
  {
      // get required fields from the config file
    $formConfig = sfConfig::get('app_form_fields');
    // Be sure to use this and not $this->formFieldSchema as it might not be
    // initiated yet.
    $formFieldSchema = $this->getFormFieldSchema();
    // For some reason I have to use the BaseForm sometimes which has no name,
    // this avoids breaking everything in such cases.
    if($this->getName() == '')
    {
        return;
    }
     if(isset($formConfig[$this->getName()]))
     {
         $requiredFields = $formConfig[$this->getName()];
     }
     // get out of here if there is no configuration for this form (the list of required fields is empty)
     if(!isset($requiredFields))
     {
         return;
     }
      foreach($this->widgetSchema->getFields() as $fieldname => $widget)
      {
          // if the config file requires this field, we set the option accordingly
          if(in_array($fieldname, $requiredFields))
          {
              $this->validatorSchema[$fieldname]->setOption('required', true);
          }
          // If the field is required we add a class to the label so it displays in the browser
          if(!is_null($this->validatorSchema[$fieldname])
                  && $this->validatorSchema[$fieldname]->getOption('required') == true)
          {
              $this->widgetSchema[$fieldname]->setLabel(
                    $formFieldSchema[$fieldname]->
                      renderLabel(null, array('class'  =>  'required_form_field'))
              );
          }
          $this->formFieldSchema = $formFieldSchema;
      }