Symfony2: Creating optgroups with an Entity type

Last week, I was working on a Symfony2 app where I wanted to generate optgroup tags inside the select box of an Entity form type. After poking around, I ran across a StackOverflow answer explaining how to do it. Basically, it turns out what you have to do is manually return a “choices” array from a class that has access to the Entity Manager. I ended up adding a method to my custom repository and passing that repository into my form:

It’s a bit messy and I’m surprised there isn’t an option on the Entity Type to pass in a callback with access to the Entity Manager to generate a choice list. Looking at the source of DoctrineType it looks like you could potentially create a custom type to extend the Entity type and then access the em from your custom function. Even that though, seems like overkill to accomplish something that is reasonably common.