Scala slick query comparison of a custom user type (enumeration) gives error - scala

Question

I'm trying to use Slick with a column that has a user defined type (an enumeration). All is working until I try to write a query that uses the column.
When compiling I get an error on the following method:
def findCredentials(credentialType:CredentialType)(implicit session: Session): List[Credential] = {
val query = for {
c <- credentials if c.credentialType === credentialType
} yield c
query.list
}
Here is the error:
[error] ... value === is not a member of
scala.slick.lifted.Column[models.domain.enumeration.CredentialType.CredentialType]
[error] c <- credentials if c.credentialType === credentialType
The enumeration code is here:
object CredentialType extends Enumeration {
type CredentialType = Value
val Password, Token = Value
}
The table definition is here:
case class Credential(id: Long, userId: Long, credentialType: CredentialType)
class Credentials(tag: Tag) extends Table[Credential](tag, "credential") {
implicit val credentialTypeColumnType = MappedColumnType.base[CredentialType, String](
{ c => c.toString },
{ s => CredentialType.withName(s)}
)
def id = column[Long]("id", O.PrimaryKey, O.AutoInc)
def userId = column[Long]("user_id")
def credentialType = column[CredentialType]("type")
def * = (id, userId, credentialType) <> (Credential.tupled, Credential.unapply)
}
I've googled a number of other questions but they're either not for slick 2.x.x or do not involve Enumeration types.
My question is, do I need to define the === operator somewhere for enumeration types, or is there a simpler way using current slick 2.0.0 functionality that I'm missing?
Thanks

Answer 1

I think you need the implicit type mapper in scope when using the === operator. You should put the
implicit val credentialTypeColumnType = MappedColumnType.base[CredentialType, String](
{ c => c.toString },
{ s => CredentialType.withName(s)}
)
somewhere where it is visible when you are creating the query.