[SPARK-27671] Fix error when casting from a nested null in a struct

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.3, 3.0.0
• Fix Version/s: 2.4.4, 3.0.0
• Component/s: SQL
• Assignee: L. C. Hsieh
• Reporter: L. C. Hsieh
• Created: 10/May/19 10:39
• Updated: 14/May/19 16:40
• Resolved: 13/May/19 19:42

Description

When a null in a nested field in struct, casting from the struct throws error, currently.

scala> sql("select cast(struct(1, null) as struct<a:int,b:int>)").show
scala.MatchError: NullType (of class org.apache.spark.sql.types.NullType$)                                                                             
  at org.apache.spark.sql.catalyst.expressions.Cast.castToInt(Cast.scala:447)                                                                          
  at org.apache.spark.sql.catalyst.expressions.Cast.cast(Cast.scala:635)                                                                               
  at org.apache.spark.sql.catalyst.expressions.Cast.$anonfun$castStruct$1(Cast.scala:603)   

scala> sql("select * FROM VALUES (('a', (10, null))), (('b', (10, 50))), (('c', null)) AS tab(x, y)").show                                             
org.apache.spark.sql.AnalysisException: failed to evaluate expression named_struct('col1', 10, 'col2', NULL): NullType (of class org.apache.spark.sql.t
ypes.NullType$); line 1 pos 14                                                                                                                         
  at org.apache.spark.sql.catalyst.analysis.package$AnalysisErrorAt.failAnalysis(package.scala:47)                                                     
  at org.apache.spark.sql.catalyst.analysis.ResolveInlineTables.$anonfun$convert$6(ResolveInlineTables.scala:106)        

Issue Links

• links to: GitHub Pull Request #24576