Github user yhuai commented on a diff in the pull request:
https://github.com/apache/spark/pull/15979#discussion_r89936859
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoder.scala
---
@@ -47,6 +47,14 @@ object ExpressionEncoder {
// We convert the not-serializable TypeTag into StructType and
ClassTag.
val mirror = typeTag[T].mirror
val tpe = typeTag[T].tpe
+
+ if (ScalaReflection.optionOfNonFlatType(tpe)) {
+ throw new UnsupportedOperationException(
+ "Cannot create encoder for Option of non-flat type, as non-flat
type is represented " +
+ "as a row, and the entire row can not be null in Spark SQL like
normal databases. " +
+ "You can wrap your type with Tuple1 if you do want top level
null objects.")
--- End diff --
Let's provide an example in the error message to help users understand how
to handle this case.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
