SlickEnumerationSupport.scala

object SlickEnumerationSupport {

  def enumerationTypeName[V <: Enumeration.Value : ClassTag] = {
    val valueSymbol = runtimeMirror.classSymbol(classTag[V].runtimeClass)
    val valueTypeName = valueSymbol.name.decodedName.toString
    val enumTypeName = valueSymbol.owner.name.decodedName.toString
    // Always use public schema
    s"${enumTypeName}_${valueTypeName}".toLowerCase
  }

  implicit def columnType[E <: Enumeration.Value](implicit tag: ClassTag[E]): BaseColumnType[E] = {
    val enum = Enumeration.forValueClass(classTag[E].runtimeClass)

    if (isH2Database) {
      MappedColumnType.base[E, String] (
        enum => enum.name,
        name => Enumeration.forValueClass(classTag[E].runtimeClass).
          withName(name).asInstanceOf[E]
      )
    } else {
      new driver.DriverJdbcType[E] {
        override val classTag: ClassTag[E] = tag
        override def sqlType: Int = java.sql.Types.OTHER
        override def sqlTypeName: String = enumerationTypeName(tag)
        override def setValue(e: E, p: PreparedStatement, idx: Int): Unit = p.setObject(idx, asPgObject(e), sqlType)
        override def getValue(r: ResultSet, idx: Int): E = {
          val value = r.getString(idx)
          if (r.wasNull) null.asInstanceOf[E] else enum.withName(value).asInstanceOf[E]
        }
        override def updateValue(e: E, r: ResultSet, idx: Int): Unit = r.updateObject(idx, asPgObject(e))
        override def valueToSQLLiteral(e: E) = if (e eq null) "NULL" else s"'${e.name}'"

        private def asPgObject(e: E) = {
          val obj = new org.postgresql.util.PGobject
          obj.setType(enumerationTypeName)
          obj.setValue(if (e eq null) null else e.name)
          obj
        }
      }
    }
  }
}