When adding custom columns to the SELECT part of a DQL statement, Doctrine makes these columns available as property of the object they are related to.

Here is a DQL example:

//Article has many Comments
SELECT c.*, a.title ArticleTitle FROM Comment c INNER JOIN c.Article a LIMIT 1
// will hydrate a Comment object looking like
-
  id: 123
  body: I completely agree
  article_id: 456
  Article:
    id: ~
    title: ~
    body: ~
    ArticleTitle: Hello, world

So that works, since I can retrieve my custom ArticleTitle column by calling $comment['Article']['ArticleTitle'].

But if I already queried this Article or this Comment objects, IdentityMap? enters the dance, and the result of the query is:

-
  id: 123
  body: I completely agree
  article_id: 456
  Article:
    id: 456
    title: Hello, World
    body: Lorem Ipsum...

The bad news is that I can no longer access my custom column by its alias: $comment['Article']['ArticleTitle'] doesn't work.

This probably means that IdentityMap? should be deactivated on queries where custom columns are added. I don't know if there is a way to do that, all I could find was to clear the identity map prior to executing the query:

Doctrine::getTable('Article')->clear();
Doctrine::getTable('Comment')->clear();

This is less than ideal, and should be handled by Doctrine rather than by the user...