[SPARK-19543] from_json fails when the input row is empty

## What changes were proposed in this pull request? Using from_json on a column with an empty string results in: java.util.NoSuchElementException: head of empty list. This is because `parser.parse(input)` may return `Nil` when `input.trim.isEmpty` ## How was this patch tested? Regression test in `JsonExpressionsSuite` Author: Burak Yavuz <[email protected]> Closes apache#16881 from brkyvz/json-fix.
DoufuX · Feb 10, 2017 · d5593f7 · d5593f7
1 parent fd6c3a0
commit d5593f7
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala
@@ -496,7 +496,7 @@ case class JsonToStruct(schema: StructType, options: Map[String, String], child:
   override def dataType: DataType = schema
 
   override def nullSafeEval(json: Any): Any = {
-    try parser.parse(json.toString).head catch {
+    try parser.parse(json.toString).headOption.orNull catch {
       case _: SparkSQLJsonProcessingException => null
     }
   }

diff --git a/...alyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/JsonExpressionsSuite.scala b/...alyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/JsonExpressionsSuite.scala
@@ -376,6 +376,14 @@ class JsonExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     )
   }
 
+  test("SPARK-19543: from_json empty input column") {
+    val schema = StructType(StructField("a", IntegerType) :: Nil)
+    checkEvaluation(
+      JsonToStruct(schema, Map.empty, Literal.create(" ", StringType)),
+      null
+    )
+  }
+
   test("to_json") {
     val schema = StructType(StructField("a", IntegerType) :: Nil)
     val struct = Literal.create(create_row(1), schema)