[SPARK-21677] json_tuple throws NullPointException when column is null as string type.

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.3.0
• Fix Version/s: 2.3.0
• Component/s: SQL
• Labels: Starter
• Assignee: Jen-Ming Chung
• Reporter: Hyukjin Kwon
• Created: 09/Aug/17 13:23
• Updated: 12/Dec/22 18:11
• Resolved: 17/Aug/17 23:37

Description

I was testing json_tuple before using this to extract values from JSONs in my testing cluster but I found it could actually throw NullPointException as below sometimes:

scala> Seq(("""{"Hyukjin": 224, "John": 1225}""")).toDS.selectExpr("json_tuple(value, trim(' Hyukjin    '))").show()
+---+
| c0|
+---+
|224|
+---+

scala> Seq(("""{"Hyukjin": 224, "John": 1225}""")).toDS.selectExpr("json_tuple(value, trim(' Jackson    '))").show()
+----+
|  c0|
+----+
|null|
+----+

scala> Seq(("""{"Hyukjin": 224, "John": 1225}""")).toDS.selectExpr("json_tuple(value, trim(null))").show()
...
java.lang.NullPointerException
	at org.apache.spark.sql.catalyst.expressions.JsonTuple$$anonfun$foldableFieldNames$1.apply(jsonExpressions.scala:367)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple$$anonfun$foldableFieldNames$1.apply(jsonExpressions.scala:366)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
	at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
	at scala.collection.AbstractTraversable.map(Traversable.scala:104)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.foldableFieldNames$lzycompute(jsonExpressions.scala:366)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.foldableFieldNames(jsonExpressions.scala:365)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.constantFields$lzycompute(jsonExpressions.scala:373)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.constantFields(jsonExpressions.scala:373)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.org$apache$spark$sql$catalyst$expressions$JsonTuple$$parseRow(jsonExpressions.scala:417)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple$$anonfun$eval$4.apply(jsonExpressions.scala:401)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple$$anonfun$eval$4.apply(jsonExpressions.scala:400)
	at org.apache.spark.util.Utils$.tryWithResource(Utils.scala:2559)
	at org.apache.spark.sql.catalyst.expressions.JsonTuple.eval(jsonExpressions.scala:400)

It sounds we should show explicit error messages or return NULL.