Make edge-case behavior of jsonb_populate_record match json_populate_record

json_populate_record throws an error if asked to convert a JSON scalar
or array into a composite type.  jsonb_populate_record was returning
a record full of NULL fields instead.  It seems better to make it
throw an error for this case as well.

Nikita Glukhov

Discussion: https://postgr.es/m/fbd1d566-bba0-a3de-d6d0-d3b1d7c24ff2@postgrespro.ru

src/backend/utils/adt/jsonfuncs.c

@@ -2682,9 +2682,24 @@ JsValueToJsObject(JsValue *jsv, JsObject *jso)
 
 		if (jbv->type == jbvBinary &&
 			JsonContainerIsObject(jbv->val.binary.data))
+		{
 			jso->val.jsonb_cont = jbv->val.binary.data;
+		}
 		else
-			jso->val.jsonb_cont = NULL;
+		{
+			bool		is_scalar;
+
+			is_scalar = IsAJsonbScalar(jbv) ||
+				(jbv->type == jbvBinary &&
+				 JsonContainerIsScalar(jbv->val.binary.data));
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 is_scalar
+					 ? errmsg("cannot call %s on a scalar",
+							  "populate_composite")
+					 : errmsg("cannot call %s on an array",
+							  "populate_composite")));
+		}
 	}
 }
 

src/test/regress/expected/jsonb.out

@@ -2276,17 +2276,9 @@ SELECT jsa FROM jsonb_populate_record(NULL::jsbrec, '{"jsa": ["aaa", null, [1, 2
 (1 row)
 
 SELECT rec FROM jsonb_populate_record(NULL::jsbrec, '{"rec": 123}') q;
- rec  
-------
- (,,)
-(1 row)
-
+ERROR:  cannot call populate_composite on a scalar
 SELECT rec FROM jsonb_populate_record(NULL::jsbrec, '{"rec": [1, 2]}') q;
- rec  
-------
- (,,)
-(1 row)
-
+ERROR:  cannot call populate_composite on an array
 SELECT rec FROM jsonb_populate_record(NULL::jsbrec, '{"rec": {"a": "abc", "c": "01.02.2003", "x": 43.2}}') q;
                 rec                
 -----------------------------------
@@ -2303,11 +2295,7 @@ SELECT reca FROM jsonb_populate_record(NULL::jsbrec, '{"reca": 123}') q;
 ERROR:  expected json array
 HINT:  see the value of key "reca"
 SELECT reca FROM jsonb_populate_record(NULL::jsbrec, '{"reca": [1, 2]}') q;
-      reca       
------------------
- {"(,,)","(,,)"}
-(1 row)
-
+ERROR:  cannot call populate_composite on a scalar
 SELECT reca FROM jsonb_populate_record(NULL::jsbrec, '{"reca": [{"a": "abc", "b": 456}, null, {"c": "01.02.2003", "x": 43.2}]}') q;
                           reca                          
 --------------------------------------------------------