Centralize json and jsonb handling of datetime types

The creates a single function JsonEncodeDateTime which will format these
data types in an efficient and consistent manner. This will be all the
more important when we come to jsonpath so we don't have to implement yet
more code doing the same thing in two more places.

This also extends the code to handle time and timetz types which were
not previously handled specially. This requires exposing the time2tm and
timetz2tm functions.

Patch from Nikita Glukhov

1 files changed, 93 insertions, 29 deletions

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 151345ab2ff..97a5b85516f 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -1504,11 +1504,69 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 			break;
 		case JSONTYPE_DATE:
 			{
+				char		buf[MAXDATELEN + 1];
+
+				JsonEncodeDateTime(buf, val, DATEOID);
+				appendStringInfo(result, "\"%s\"", buf);
+			}
+			break;
+		case JSONTYPE_TIMESTAMP:
+			{
+				char		buf[MAXDATELEN + 1];
+
+				JsonEncodeDateTime(buf, val, TIMESTAMPOID);
+				appendStringInfo(result, "\"%s\"", buf);
+			}
+			break;
+		case JSONTYPE_TIMESTAMPTZ:
+			{
+				char		buf[MAXDATELEN + 1];
+
+				JsonEncodeDateTime(buf, val, TIMESTAMPTZOID);
+				appendStringInfo(result, "\"%s\"", buf);
+			}
+			break;
+		case JSONTYPE_JSON:
+			/* JSON and JSONB output will already be escaped */
+			outputstr = OidOutputFunctionCall(outfuncoid, val);
+			appendStringInfoString(result, outputstr);
+			pfree(outputstr);
+			break;
+		case JSONTYPE_CAST:
+			/* outfuncoid refers to a cast function, not an output function */
+			jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
+			outputstr = text_to_cstring(jsontext);
+			appendStringInfoString(result, outputstr);
+			pfree(outputstr);
+			pfree(jsontext);
+			break;
+		default:
+			outputstr = OidOutputFunctionCall(outfuncoid, val);
+			escape_json(result, outputstr);
+			pfree(outputstr);
+			break;
+	}
+}
+
+/*
+ * Encode 'value' of datetime type 'typid' into JSON string in ISO format using
+ * optionally preallocated buffer 'buf'.
+ */
+char *
+JsonEncodeDateTime(char *buf, Datum value, Oid typid)
+{
+	if (!buf)
+		buf = palloc(MAXDATELEN + 1);
+
+	switch (typid)
+	{
+		case DATEOID:
+			{
 				DateADT		date;
 				struct pg_tm tm;
-				char		buf[MAXDATELEN + 1];
 
-				date = DatumGetDateADT(val);
+				date = DatumGetDateADT(value);
+
 				/* Same as date_out(), but forcing DateStyle */
 				if (DATE_NOT_FINITE(date))
 					EncodeSpecialDate(date, buf);
@@ -1518,17 +1576,40 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
 					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
 				}
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
-		case JSONTYPE_TIMESTAMP:
+		case TIMEOID:
+			{
+				TimeADT		time = DatumGetTimeADT(value);
+				struct pg_tm tt,
+						   *tm = &tt;
+				fsec_t		fsec;
+
+				/* Same as time_out(), but forcing DateStyle */
+				time2tm(time, tm, &fsec);
+				EncodeTimeOnly(tm, fsec, false, 0, USE_XSD_DATES, buf);
+			}
+			break;
+		case TIMETZOID:
+			{
+				TimeTzADT  *time = DatumGetTimeTzADTP(value);
+				struct pg_tm tt,
+						   *tm = &tt;
+				fsec_t		fsec;
+				int			tz;
+
+				/* Same as timetz_out(), but forcing DateStyle */
+				timetz2tm(time, tm, &fsec, &tz);
+				EncodeTimeOnly(tm, fsec, true, tz, USE_XSD_DATES, buf);
+			}
+			break;
+		case TIMESTAMPOID:
 			{
 				Timestamp	timestamp;
 				struct pg_tm tm;
 				fsec_t		fsec;
-				char		buf[MAXDATELEN + 1];
 
-				timestamp = DatumGetTimestamp(val);
+				timestamp = DatumGetTimestamp(value);
 				/* Same as timestamp_out(), but forcing DateStyle */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
 					EncodeSpecialTimestamp(timestamp, buf);
@@ -1538,19 +1619,17 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
-		case JSONTYPE_TIMESTAMPTZ:
+		case TIMESTAMPTZOID:
 			{
 				TimestampTz timestamp;
 				struct pg_tm tm;
 				int			tz;
 				fsec_t		fsec;
 				const char *tzn = NULL;
-				char		buf[MAXDATELEN + 1];
 
-				timestamp = DatumGetTimestampTz(val);
+				timestamp = DatumGetTimestampTz(value);
 				/* Same as timestamptz_out(), but forcing DateStyle */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
 					EncodeSpecialTimestamp(timestamp, buf);
@@ -1560,29 +1639,14 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
-		case JSONTYPE_JSON:
-			/* JSON and JSONB output will already be escaped */
-			outputstr = OidOutputFunctionCall(outfuncoid, val);
-			appendStringInfoString(result, outputstr);
-			pfree(outputstr);
-			break;
-		case JSONTYPE_CAST:
-			/* outfuncoid refers to a cast function, not an output function */
-			jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
-			outputstr = text_to_cstring(jsontext);
-			appendStringInfoString(result, outputstr);
-			pfree(outputstr);
-			pfree(jsontext);
-			break;
 		default:
-			outputstr = OidOutputFunctionCall(outfuncoid, val);
-			escape_json(result, outputstr);
-			pfree(outputstr);
-			break;
+			elog(ERROR, "unknown jsonb value datetime type oid %d", typid);
+			return NULL;
 	}
+
+	return buf;
 }
 
 /*