MaxGekk commented on a change in pull request #27759: [SPARK-31008][SQL]Support
json_array_length function
URL: https://github.com/apache/spark/pull/27759#discussion_r387499401
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala
##########
@@ -781,3 +782,65 @@ case class SchemaOfJson(
override def prettyName: String = "schema_of_json"
}
+
+/**
+ * A function that returns number of elements in outer Json Array.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(jsonArray) - Returns length of the jsonArray",
+ arguments = """
+ jsonArray - A JSON array is required as argument. `Analysis Exception` is
thrown if any other
+ valid JSON expression is passed. `NULL` is returned in case of invalid
JSON.
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_('[1,2,3,4]');
+ 4
+ > SELECT _FUNC_('[1,2,3,{"f1":1,"f2":[5,6]},4]');
Review comment:
Should the expression support array of different element types? For
instance, `from_json()` can parse arrays only of particular type. So, you can
get length but cannot parse it by `from_json`.
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