Github user MaxGekk commented on a diff in the pull request:
https://github.com/apache/spark/pull/21439#discussion_r194491865
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/json/JacksonParser.scala
---
@@ -101,6 +102,13 @@ class JacksonParser(
}
}
+ private def makeArrayRootConverter(at: ArrayType): JsonParser =>
Seq[InternalRow] = {
+ val elemConverter = makeConverter(at.elementType)
+ (parser: JsonParser) => parseJsonToken[Seq[InternalRow]](parser, at) {
+ case START_ARRAY => Seq(InternalRow(convertArray(parser,
elemConverter)))
--- End diff --
The code in line 87 returns `null` for json input `[]` if schema is
`StructType(StructField("a", IntegerType) :: Nil)`. I would explain why we
should return `null` in that case: we *extract* struct from the array. If the
array is _empty_, it means there is nothing to extract and we returns `null`
for the nothing.
In case when schema is `ArrayType(...)`, I believe we should return
`empty` array for empty JSON array `[]`
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