How to return a case class in map function?

[Yan Facai]

Hi, all.
When I use a case class as return value in map function, spark always raise
a ClassCastException.

I write an demo, like:

scala> case class Record(key: Int, value: String)

scala> case class ID(key: Int)

scala> val df = Seq(Record(1, "a"), Record(2, "b")).toDF

scala> df.map{x => ID(x.getInt(0))}.show

16/11/02 14:52:34 ERROR Executor: Exception in task 0.0 in stage 166.0 (TID
175)
java.lang.ClassCastException: $line1401.$read$$iw$$iw$ID cannot be cast to
$line1401.$read$$iw$$iw$ID
        at
org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown
Source)


Please tell me if I'm wrong.
Thanks.