dongjoon-hyun commented on a change in pull request #27836: [SPARK-31009][SQL]
Support json_object_keys function
URL: https://github.com/apache/spark/pull/27836#discussion_r400638874
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala
##########
@@ -796,3 +797,64 @@ case class SchemaOfJson(
override def prettyName: String = "schema_of_json"
}
+
+/**
+ * A function which returns all the keys of outer JSON object.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(json_object) - returns all the keys of outer JSON object.",
+ arguments = """
+ Arguments:
+ * json_object - A JSON object. If it is an invalid string, the function
returns null.
+ If it is a JSON array or null, a runtime exception will be thrown.
+ """,
+ examples = """
+ Examples:
+ > Select _FUNC_('{}');
+ []
+ > Select _FUNC_('{"key": "value"}');
+ ["key"]
+ > Select _FUNC_('{"f1":"abc","f2":{"f3":"a", "f4":"b"}}');
+ ["f1","f2"]
+ """,
+ since = "3.1.0")
+case class JsonObjectKeys(child: Expression) extends UnaryExpression with
CodegenFallback {
+ override def dataType: DataType = ArrayType(StringType)
+ override def nullable: Boolean = true
+ override def prettyName: String = "json_object_keys"
+
+ override def eval(input: InternalRow): Any = {
+ try {
+ val json = child.eval(input).asInstanceOf[UTF8String]
+
Utils.tryWithResource(CreateJacksonParser.utf8String(SharedFactory.jsonFactory,
json)) {
+ parser => getJsonKeys(parser, input)
+ }
+ } catch {
+ case _: JsonProcessingException => null
+ }
Review comment:
I checked.
```
scala> sql("select json_object_keys(null)").show
java.lang.NullPointerException
scala> sql("select json_object_keys(1)").show
java.lang.ClassCastException: class java.lang.Integer cannot be cast to
class org.apache.spark.unsafe.types.UTF8String (java.lang.Integer is in module
java.base of loader 'bootstrap'; org.apache.spark.unsafe.types.UTF8String is in
unnamed module of loader 'app')
```
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