a986fe013e
People like me think the problem is that there is no association mapping, when the problem in fact could be that there also is a field mapping on the property. This message makes it clearer why we are getting an error message.
Doctrine 2 ORM
Master: 
2.3: 
2.2: 
2.1: 
Doctrine 2 is an object-relational mapper (ORM) for PHP 5.3.2+ that provides transparent persistence for PHP objects. It sits on top of a powerful database abstraction layer (DBAL). One of its key features is the option to write database queries in a proprietary object oriented SQL dialect called Doctrine Query Language (DQL), inspired by Hibernates HQL. This provides developers with a powerful alternative to SQL that maintains flexibility without requiring unnecessary code duplication.