Save form data to multi-value field on MongoDB using Play2.2.2

Question

I'm experimenting with play (v2.2.2), and I have it connected to MongoDB (v2.4.6) using jackson.

I have a models.Role class with the following attributes:

@Id
@ObjectId
public String id;

public String name;
public ArrayList<String> permissions;

On the template (roles.scala.html), I can easily get the list of permissions to be printed on the HTML, but when I try to add a new role passing a single permission as a string in the form as an @InputText field, it does not get recorded in MongoDB. I suppose that it is because play/scala is trying to assign a simple String to an ArrayList<String>.

Any ideas on the propper approach? Maybe I should do some logic on the create() method under Role class?