From: Andrew Dunstan <andrew@dunslane.net>
Date: Thu, 25 Sep 2014 12:18:18 +0000 (-0400)
Subject: Return NULL from json_object_agg if it gets no rows.
X-Git-Tag: jit-before-rebase-2017-11-03~6509
X-Git-Url: http://git.postgresql.org/gitweb/static/4.16?a=commitdiff_plain;h=ecacbdbcee67e202cfcaa1180da170b9f13654bb;p=users%2Fandresfreund%2Fpostgres.git

Return NULL from json_object_agg if it gets no rows.

This makes it consistent with the docs and with all other builtin
aggregates apart from count().
---

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 19d74014ef..c52f6732b0 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -1948,7 +1948,7 @@ json_object_agg_finalfn(PG_FUNCTION_ARGS)
 	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);
 
 	if (state == NULL)
-		PG_RETURN_TEXT_P(cstring_to_text("{}"));
+		PG_RETURN_NULL();
 
 	appendStringInfoString(state, " }");