/** * Filter the query by a related Book object * * @param Book|PropelCollection $book The related object(s) to use as filter * @param string $comparison Operator to use for the column comparison, defaults to Criteria::EQUAL * * @return ItemQuery The current query, for fluid interface */ public function filterByBook($book, $comparison = null) { if ($book instanceof Book) { return $this->addUsingAlias(ItemPeer::ISBN, $book->getIsbn(), $comparison); } elseif ($book instanceof PropelCollection) { if (null === $comparison) { $comparison = Criteria::IN; } return $this->addUsingAlias(ItemPeer::ISBN, $book->toKeyValue('PrimaryKey', 'Isbn'), $comparison); } else { throw new PropelException('filterByBook() only accepts arguments of type Book or PropelCollection'); } }