address comment

cloud-fan · cloud-fan · commit 01b072d07a21 · 2016-11-29T19:42:33.000+08:00
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoder.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoder.scala
@@ -52,7 +52,8 @@ object ExpressionEncoder {
       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.")
+          "You can wrap your type with Tuple1 if you do want top level null objects, e.g. " +
+          "val ds: Dataset[Tuple1[MyClass]] = Seq(Tuple1(MyClass(...)), Tuple1(null)).toDS")
     }
 
     val cls = mirror.runtimeClass(tpe)

Original file line number	Diff line number	Diff line change
`@@ -52,7 +52,8 @@ object ExpressionEncoder {`
`52`	`52`	`throw new UnsupportedOperationException(`
`53`	`53`	`"Cannot create encoder for Option of non-flat type, as non-flat type is represented " +`
`54`	`54`	`"as a row, and the entire row can not be null in Spark SQL like normal databases. " +`
`55`		`- "You can wrap your type with Tuple1 if you do want top level null objects.")`
	`55`	`+ "You can wrap your type with Tuple1 if you do want top level null objects, e.g. " +`
	`56`	`+ "val ds: Dataset[Tuple1[MyClass]] = Seq(Tuple1(MyClass(...)), Tuple1(null)).toDS")`
`56`	`57`	`}`
`57`	`58`
`58`	`59`	`val cls = mirror.runtimeClass(tpe)`