Output timestamps in ISO 8601 format when rendering JSON.

Many JSON processors require timestamp strings in ISO 8601 format in
order to convert the strings. When converting a timestamp, with or
without timezone, to a JSON datum we therefore now use such a format
rather than the type's default text output, in functions such as
to_json().

This is a change in behaviour from 9.2 and 9.3, as noted in the release
notes.

diff --git a/doc/src/sgml/release-9.4.sgml b/doc/src/sgml/release-9.4.sgml
index c0ead175d30e21b09f617bf5835514176ad52c25..08307c8f667c72f1bce7afd716ceeb830d697f7e 100644 (file)
--- a/doc/src/sgml/release-9.4.sgml
+++ b/doc/src/sgml/release-9.4.sgml
@@ -162,6 +162,24 @@
      </para>
     </listitem>
 
+    <listitem>
+     <para>
+      Values of type
+      <link linkend="datatype-datetime"><type>timestamp</></link>  and
+      <link linkend="datatype-datetime"><type>timestamptz</></link> are now
+      rendered in a string format compliant with ISO 8601 rather than the
+      default output format when converting to or used in
+      <link linkend="datatype-json"><type>JSON</type></link>.
+      (Andrew Dunstan)
+     </para>
+
+     <para>
+      Previously these were rendered in the default text output format
+      for the type, but many JSON processors require timestamps in ISO 8601
+      format.
+     </para>
+    </listitem>
+
     <listitem>
      <para>
       Rename <link linkend="SQL-EXPLAIN"><command>EXPLAIN

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index a7364f30f847fd2f37c57c4512e19ea429c1078b..2462111ecb3050cd0836677dda85e24fbd747860 100644 (file)
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -24,6 +24,7 @@
 #include "parser/parse_coerce.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/formatting.h"
 #include "utils/lsyscache.h"
 #include "utils/json.h"
 #include "utils/jsonapi.h"
@@ -53,6 +54,8 @@ typedef enum                                  /* type categories for datum_to_json */
        JSONTYPE_NULL,                          /* null, so we didn't bother to identify */
        JSONTYPE_BOOL,                          /* boolean (built-in types only) */
        JSONTYPE_NUMERIC,                       /* numeric (ditto) */
+       JSONTYPE_TIMESTAMP,         /* we use special formatting for timestamp */
+       JSONTYPE_TIMESTAMPTZ,       /* ... and timestamptz */
        JSONTYPE_JSON,                          /* JSON itself (and JSONB) */
        JSONTYPE_ARRAY,                         /* array */
        JSONTYPE_COMPOSITE,                     /* composite */
@@ -60,6 +63,13 @@ typedef enum                                 /* type categories for datum_to_json */
        JSONTYPE_OTHER                          /* all else */
 } JsonTypeCategory;
 
+/*
+ * to_char formats to turn timestamps and timpstamptzs into json strings
+ * that are ISO 8601 compliant
+ */
+#define TS_ISO8601_FMT "\\\"YYYY-MM-DD\"T\"HH24:MI:SS.US\\\""
+#define TSTZ_ISO8601_FMT "\\\"YYYY-MM-DD\"T\"HH24:MI:SS.USOF\\\""
+
 static inline void json_lex(JsonLexContext *lex);
 static inline void json_lex_string(JsonLexContext *lex);
 static inline void json_lex_number(JsonLexContext *lex, char *s, bool *num_err);
@@ -1262,6 +1272,14 @@ json_categorize_type(Oid typoid,
                        *tcategory = JSONTYPE_NUMERIC;
                        break;
 
+               case TIMESTAMPOID:
+                       *tcategory = JSONTYPE_TIMESTAMP;
+                       break;
+
+               case TIMESTAMPTZOID:
+                       *tcategory = JSONTYPE_TIMESTAMPTZ;
+                       break;
+
                case JSONOID:
                case JSONBOID:
                        *tcategory = JSONTYPE_JSON;
@@ -1375,6 +1393,29 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
                        }
                        pfree(outputstr);
                        break;
+               case JSONTYPE_TIMESTAMP:
+                       /*
+                        * The timestamp format used here provides for quoting the string,
+                        * so no escaping is required.
+                        */
+                       jsontext = DatumGetTextP(
+                               DirectFunctionCall2(timestamp_to_char, val,
+                                                                       CStringGetTextDatum(TS_ISO8601_FMT)));
+                       outputstr = text_to_cstring(jsontext);
+                       appendStringInfoString(result, outputstr);
+                       pfree(outputstr);
+                       pfree(jsontext);
+                       break;
+               case JSONTYPE_TIMESTAMPTZ:
+                       /* same comment as for timestamp above */
+                       jsontext = DatumGetTextP(
+                               DirectFunctionCall2(timestamptz_to_char, val,
+                                                                       CStringGetTextDatum(TSTZ_ISO8601_FMT)));
+                       outputstr = text_to_cstring(jsontext);
+                       appendStringInfoString(result, outputstr);
+                       pfree(outputstr);
+                       pfree(jsontext);
+                       break;
                case JSONTYPE_JSON:
                        /* JSON and JSONB output will already be escaped */
                        outputstr = OidOutputFunctionCall(outfuncoid, val);

diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index 9f086763c253998821c6077252af50faafbce779..c4dc8b0e3cb73f07ece801a7e8893ddf3b730b76 100644 (file)
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -403,6 +403,29 @@ SELECT row_to_json(row((select array_agg(x) as d from generate_series(5,10) x)),
  {"f1":[5,6,7,8,9,10]}
 (1 row)
 
+-- to_json, timestamps
+select to_json(timestamp '2014-05-28 12:22:35.614298');
+           to_json            
+------------------------------
+ "2014-05-28T12:22:35.614298"
+(1 row)
+
+BEGIN;
+SET LOCAL TIME ZONE 10.5;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+              to_json               
+------------------------------------
+ "2014-05-29T02:52:35.614298+10:30"
+(1 row)
+
+SET LOCAL TIME ZONE -8;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+             to_json             
+---------------------------------
+ "2014-05-28T08:22:35.614298-08"
+(1 row)
+
+COMMIT;
 --json_agg
 SELECT json_agg(q)
   FROM ( SELECT $$a$$ || x AS b, y AS c,

diff --git a/src/test/regress/expected/json_1.out b/src/test/regress/expected/json_1.out
index 13f7687608edd720ca5c218df3866c768e9dd366..629e98e6c5f26952af1d01f2259ba7a2c160b473 100644 (file)
--- a/src/test/regress/expected/json_1.out
+++ b/src/test/regress/expected/json_1.out
@@ -403,6 +403,29 @@ SELECT row_to_json(row((select array_agg(x) as d from generate_series(5,10) x)),
  {"f1":[5,6,7,8,9,10]}
 (1 row)
 
+-- to_json, timestamps
+select to_json(timestamp '2014-05-28 12:22:35.614298');
+           to_json            
+------------------------------
+ "2014-05-28T12:22:35.614298"
+(1 row)
+
+BEGIN;
+SET LOCAL TIME ZONE 10.5;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+              to_json               
+------------------------------------
+ "2014-05-29T02:52:35.614298+10:30"
+(1 row)
+
+SET LOCAL TIME ZONE -8;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+             to_json             
+---------------------------------
+ "2014-05-28T08:22:35.614298-08"
+(1 row)
+
+COMMIT;
 --json_agg
 SELECT json_agg(q)
   FROM ( SELECT $$a$$ || x AS b, y AS c,

diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index 2ae5b8279902e741c17ab673509c9e261662b63b..6c2faeccd30d2c64114709d659ca7454f62ffd80 100644 (file)
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -100,6 +100,17 @@ FROM rows q;
 
 SELECT row_to_json(row((select array_agg(x) as d from generate_series(5,10) x)),false);
 
+-- to_json, timestamps
+
+select to_json(timestamp '2014-05-28 12:22:35.614298');
+
+BEGIN;
+SET LOCAL TIME ZONE 10.5;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+SET LOCAL TIME ZONE -8;
+select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
+COMMIT;
+
 --json_agg
 
 SELECT json_agg(q)