我正在学习sparksql，并尝试在创建的数据集中应用过滤器。我定义了一个简单的employee case类，它有3个字段：name、salary和dpt。

case class Employee( name: String, salary: Double, age: Int, dpt: Dept)

最后一个字段dpt的定义如下：

sealed trait Dept extends { val name: String }

  case object Accountability extends Dept { override val name = "AC"}
  case object Sales extends Dept { override val name = "S"}
  case object Finance extends Dept { override val name = "F"}
  case object Marketing extends Dept { override val name = "M"}
  case object Communication extends Dept { override val name = "C"}
  case object Reception extends Dept { override val name = "R"}
  case object HumanResource extends Dept { override val name = "HR"}

我已经尝试使用kryo编码器来解决它，但它不工作。

object DeptEncoders {
    implicit def deptEncoder : org.apache.spark.sql.Encoder[Dept] = org.apache.spark.sql.Encoders.kryo[Dept]
  }