I've been playing around with Symfony on my web server and I've been creating entity with doctrine for my database. I wanted to add a column to one of these entity... I wanted to do something like:
php app/console doctrine:modify:entity
Actually, using Doctrine does not make sense at all to do something like you suggested.
Doctrine is a ORM (Object-Relational Mapping) tool. It means that you want to abstract the database from your PHP code, you delegate database stuff to Doctrine. Doctrine does a wonderful job on that area.
As you want to keep your customers/peers updated with the latest version of the model, you should use the Doctrine Migrations ( http://symfony.com/doc/current/bundles/DoctrineMigrationsBundle/index.html ). That's the way to manage database updates. Moreover, it gives you complete control on what to do when upgrading/downgrading the database. You could, e.g., set default values before you add the FK.
The steps for adding a new property on the class should be:
modify the class by:
Acme\MyBundle\Entity\Customer and add the property you want;
or modify the doctrine file:
run the console command (it will add the proper set/get in the class)
php app/console doctrine:generate:entities AcmeMyBundle:Customer
run the console command
php app/console doctrine:migrations:diff
run the console command (it will place a new file on app/DoctrineMigrations)
php app/console doctrine:migrations:migrate
When you're deploying the new version of the code, all you got to do is update the source code and run the command above.