Michael Kimsal has pointed out a small irritation when using the Symfony framework and models - an issue when using models that have relationships.

If there are relations (an Author has a Book, for example). the generated forms will complain that the generated Models need a __toString() method to be used in the Form/View. In grails, this is the case, but every domain (corresponding to a Symfony 'model') has an implicit toString() method already generated, which return the string ":". For most production work, you’ll want to override it with whatever you need the string to read, but for prototyping, it's fine.

He went in and modified the Symfony core to add in a __toString call that would return the object correctly. Several of the commentors agree with his frustration and some of the Symfony developers even chime in with some of the reasoning behind why it's like that.