Outputting required field indicator for symfony forms

I have a few forms configured in symfony. One things I need is to have an asterisk (*) or other indicator next to fields that are required. The fields are all set to required int he form framework, and return a "this field is required" error when the form is submitted, but I want an indicator before the form is submitted.

If there any way to do this without overriding the labels for each field manually?

Here's an automatic solution found in Kris Wallsmith's blog:

lib/formatter/RequiredLabelsFormatterTable.class.php, this will add a 'required' class to the labels of required fields

<?php

class RequiredLabelsFormatterTable extends sfWidgetFormSchemaFormatterTable
{
  protected
    $requiredLabelClass = 'required';

  public function generateLabel($name, $attributes = array())
  {
    // loop up to find the "required_fields" option
    $widget = $this->widgetSchema;
    do {
      $requiredFields = (array) $widget->getOption('required_fields');
    } while ($widget = $widget->getParent());

    // add a class (non-destructively) if the field is required
    if (in_array($this->widgetSchema->generateName($name), $requiredFields)) {
      $attributes['class'] = isset($attributes['class']) ?
        $attributes['class'].' '.$this->requiredLabelClass :
        $this->requiredLabelClass;
    }

    return parent::generateLabel($name, $attributes);
  }
}

lib/form/BaseForm.class.php, this is the common base class for all the forms in your project:

  protected function getRequiredFields(sfValidatorSchema $validatorSchema = null, $format = null)
  {
    if (is_null($validatorSchema)) {
      $validatorSchema = $this->validatorSchema;
    }

    if (is_null($format)) {
      $format = $this->widgetSchema->getNameFormat();
    }

    $fields = array();

    foreach ($validatorSchema->getFields() as $name => $validator) {
      $field = sprintf($format, $name);
      if ($validator instanceof sfValidatorSchema) {
        // recur
        $fields = array_merge(
          $fields,
          $this->getRequiredFields($validator, $field.'[%s]')
        );
      } else if ($validator->getOption('required')) {
        // this field is required
        $fields[] = $field;
      }
    }

    return $fields;
  }  

add the following few lines to BaseForm as well, in the __construct() method:

$this->widgetSchema->addOption("required_fields", $this->getRequiredFields());
$this->widgetSchema->addFormFormatter('table',
  new RequiredLabelsFormatterTable($this->widgetSchema)
);   

After all this, all your labels will have the required class, use whatever css you need to mark it to the user.