ganeshashree commented on code in PR #58034:
URL: https://github.com/apache/spark/pull/58034#discussion_r4048042024
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala:
##########
@@ -2210,3 +2243,347 @@ case class JsonTypeof(child: Expression)
override protected def withNewChildInternal(newChild: Expression):
JsonTypeof =
copy(child = newChild)
}
+
+/**
+ * The SQL:2016 `JSON_OBJECT` constructor function (feature T811): constructs
a JSON object from
+ * key-value pairs, written `key VALUE value`, `KEY key VALUE value`, `key :
value`, or the
+ * MySQL-style `key, value`.
+ *
+ * Keys must be non-null strings; a null key is an error. The `ON NULL` clause
controls whether
+ * null-valued pairs are included (NULL ON NULL, the standard default) or
omitted (ABSENT ON NULL).
+ *
+ * A value is spliced in raw (unquoted) only when it is a lexically nested
JSON constructor
+ * (implicit `FORMAT JSON`, tracked by `rawJson`). The standard's explicit
value-level `FORMAT JSON`
+ * clause (e.g. `JSON_OBJECT('a' VALUE '{"b":1}' FORMAT JSON)`) is deferred.
+ *
+ * Examples:
+ * JSON_OBJECT('id' VALUE 7, 'name' VALUE 'Ada') ->
'{"id":7,"name":"Ada"}'
+ * JSON_OBJECT('id': 7, 'v': NULL) -> '{"id":7,"v":null}'
+ * JSON_OBJECT('id': 7, 'v': NULL ABSENT ON NULL) -> '{"id":7}'
+ * JSON_OBJECT() -> '{}'
+ *
+ * A flat, clause-free call routes through function resolution and is rebuilt
by
+ * `JsonObjectExpressionBuilder` (so a same-named routine can shadow the
built-in `json_object`); a
+ * clause-bearing or nested form is built directly from the grammar (see
+ * `AstBuilder.visitJsonObject`). The user-facing reference lives in
+ * `docs/sql-ref-syntax-qry-select-json-object.md`.
+ */
+case class JsonObjectExpr(
+ members: Seq[(Expression, Expression)],
+ rawJson: Seq[Boolean],
+ nullBehavior: JsonConstructorNullBehavior =
JsonConstructorNullBehavior.Null,
+ returning: DataType = StringType,
+ timeZoneId: Option[String] = None)
+ extends Expression
+ with TimeZoneAwareExpression
+ with CodegenFallback
+ with QueryErrorsBase
+ // Default RETURNING is a plain STRING, so
`DefaultStringProducingExpression` lets
+ // `ApplyDefaultCollation` cast the result to a non-default collation; the
`dataType` override
+ // below stays authoritative when RETURNING is given explicitly.
+ with DefaultStringProducingExpression
+ with ImplicitlyFormattedAsJson {
+
+ // `rawJson(i)` marks member `i`'s value as already-JSON text to splice
verbatim, not quote; it is
+ // frozen at parse time (see `AstBuilder.visitJsonObject`,
[[ImplicitlyFormattedAsJson]]).
+ require(members.length == rawJson.length,
+ "JsonObjectExpr requires one rawJson flag per member")
+
+ @transient private lazy val memberArray: Array[(Expression, Expression)] =
+ members.toArray
+
+ @transient private lazy val rawJsonArray: Array[Boolean] =
+ rawJson.toArray
+
+ // Always throwable: a null key raises JSON_OBJECT_NULL_KEY at eval even
with non-throwable
+ // children, which keeps the optimizer from pushing it below a filtering
join. Left non-foldable
+ // (the default) so folding a constant call does not eagerly raise that
null-key error at
+ // optimization for rows a filter would later drop.
+ override lazy val throwable: Boolean = true
+
+ // The value is never null, but report nullable as `throwable` (like
JsonArray): `NullPropagation`
+ // keys off `nullable`, so a non-nullable constructor would let it fold `IS
[NOT] NULL` to a
+ // constant or `count(...)` to `count(1)`, skipping the eval that must raise
JSON_OBJECT_NULL_KEY.
+ override def nullable: Boolean = throwable
+
+ override def dataType: DataType = returning
+
+ override def children: Seq[Expression] =
+ memberArray.flatMap { case (k, v) => Seq(k, v) }.toImmutableArraySeq
Review Comment:
Done.
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