plop.php

<?php
// example of a locally computed virtual property
class Book extends Doctrine_Record
{
  public function getSynopsys($length = 200)
  {
    return substr($this->abstract.$this->cover, 0, $length);
  }
  
  public function setSynopsys($value)
  {
    throw new LogicException('cannot set a computed field');
  }
}

$book = BookTable::getInstance()->findOneByTitle('Les Misérables');
echo $book->getSynopsys();

// example of a SQL computed virtual property
class BookTable extends Doctrine_Table
{
  public function getWithAuthorsCount()
  {
    return $this->createQuery('b')
      ->addSelect('COUNT(a.id) as nb_authors')
      ->leftJoin('b.Authors a')
      ->groupBy('b.id, a.id')
      ->execute()
    ;
  }
}

for (BookTable::getInstance()->getWithAuthorsCount() as $book)
{
  echo sprintf('%s (%d author(s))', $book->title, $book->nb_authors);
}