How to manage scala enum with Anorm? - scala

Question

I want to create user roles by using enums (thought that it would be the best idea).
How should I proceed with this?
My current code looks like this:
object UserRole extends Enumeration {
type UserRole = Value
val admin, user, manager = Value
}
case class User(id: Long, firstname: String, lastname: String, password: String, email: String, role: UserRole)
So how should I define the user "simple":
val simple = {
get[Long]("user.id") ~
get[String]("user.firstname") ~
get[String]("user.lastname") ~
get[String]("user.password") ~
get[String]("user.email") ~
get[UserRole]("user.role") map {
case id~firstname~lastname~password~email~role => User(id, firstname, lastname, password, email, role)
}
}
And how should I save it to database?
CREATE TABLE user (
id integer NOT NULL DEFAULT nextval('user_id_seq'),
firstname varchar(60),
lastname varchar(60),
password varchar(255),
email varchar(60),
role varchar(40)
);

Answer 1

Anorm doesn't support scala enums (and scala enums are pretty bad, in my opinion). What I usually do is create another case class with it's own parser and table space, and JOIN it to relevant queries. The UserRole can be parsed in User by composing it within User.simple.
case class UserRole(id: Long, name: String)
object UserRole {
val simple: RowParser[UserRole] = {
get[Long]("roles.id") ~
get[String]("roles.name") map {
case id~name => UserRole(id, name)
}
}
}
case class User(id: Long, firstname: String, lastname: String, password: String, email: String, role: UserRole)
object User {
val simple: RowParser[User] = {
get[Long]("user.id") ~
get[String]("user.firstname") ~
get[String]("user.lastname") ~
get[String]("user.password") ~
get[String]("user.email") ~
UserRole.simple map {
case id~firstname~lastname~password~email~role =>
User(id, firstname, lastname, password, email, role)
}
}
}

Answer 2

As another alternative, you could model your roles as with a sealed trait.
sealed trait UserRole
case object Admin extends UserRole
case object User extends UserRole
case object Manager extends UserRole
Then provide a anorm reader for your type.
implicit val column: Column[UserRole] = {
Column.nonNull1 { (value, meta) =>
val MetaDataItem(qualified, nullable, clazz) = meta
value match {
case "Admin" => Right(Admin)
case "User" => Right(User)
case "Manager" => Right(Manager)
case unknown => Left(TypeDoesNotMatch(s"unknown UserRole from $unknown"))
}
}
}
Then you can use the type in your row parser like get[UserRole]
Note the matching on the string, the obviously a pretty budget but you get the idea.
For more details see the docs here, https://playframework.com/documentation/2.4.x/ScalaAnorm#Column-parsers