Correctly handle NULLs in JSON output.

Error reported by David Wheeler.

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index d7db4cf0cf93534d5173d5c338cf67063258d674..2968c57e3f88e15e3ff1026d5dc1985b09a3b63a 100644 (file)
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -79,9 +79,10 @@ static void report_parse_error(JsonParseStack *stack, JsonLexContext *lex);
 static void report_invalid_token(JsonLexContext *lex);
 static char *extract_mb_char(char *s);
 static void composite_to_json(Datum composite, StringInfo result, bool use_line_feeds);
-static void array_dim_to_json(StringInfo result, int dim, int ndims,int * dims,
-                                                         Datum *vals, int * valcount, TYPCATEGORY tcategory,
-                                                         Oid typoutputfunc, bool use_line_feeds);
+static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
+                                                         Datum *vals, bool *nulls, int *valcount, 
+                                                         TYPCATEGORY tcategory, Oid typoutputfunc, 
+                                                         bool use_line_feeds);
 static void array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds);
 
 /* fake type category for JSON so we can distinguish it in datum_to_json */
@@ -682,13 +683,13 @@ extract_mb_char(char *s)
  * composite_to_json or array_to_json_internal as appropriate.
  */
 static inline void
-datum_to_json(Datum val, StringInfo result, TYPCATEGORY tcategory,
+datum_to_json(Datum val, bool is_null, StringInfo result, TYPCATEGORY tcategory,
                          Oid typoutputfunc)
 {
 
        char *outputstr;
 
-       if (val == (Datum) NULL)
+       if (is_null)
        {
                appendStringInfoString(result,"null");
                return;
@@ -742,8 +743,8 @@ datum_to_json(Datum val, StringInfo result, TYPCATEGORY tcategory,
  */
 static void
 array_dim_to_json(StringInfo result, int dim, int ndims,int * dims, Datum *vals,
-                                 int * valcount, TYPCATEGORY tcategory, Oid typoutputfunc,
-                                 bool use_line_feeds)
+                                 bool *nulls, int * valcount, TYPCATEGORY tcategory, 
+                                 Oid typoutputfunc, bool use_line_feeds)
 {
 
        int i;
@@ -762,7 +763,8 @@ array_dim_to_json(StringInfo result, int dim, int ndims,int * dims, Datum *vals,
 
                if (dim + 1 == ndims)
                {
-                       datum_to_json(vals[*valcount],result,tcategory,typoutputfunc);
+                       datum_to_json(vals[*valcount], nulls[*valcount], result, tcategory,
+                                                 typoutputfunc);
                        (*valcount)++;
                }
                else
@@ -771,8 +773,8 @@ array_dim_to_json(StringInfo result, int dim, int ndims,int * dims, Datum *vals,
                         * Do we want line feeds on inner dimensions of arrays?
                         * For now we'll say no.
                         */
-                       array_dim_to_json(result, dim+1, ndims, dims, vals, valcount,
-                                                         tcategory,typoutputfunc,false);
+                       array_dim_to_json(result, dim+1, ndims, dims, vals, nulls,
+                                                         valcount, tcategory, typoutputfunc, false);
                }
        }
 
@@ -827,7 +829,7 @@ array_to_json_internal(Datum array, StringInfo result, bool use_line_feeds)
        else
                tcategory = TypeCategory(element_type);
 
-       array_dim_to_json(result, 0, ndim, dim, elements, &count, tcategory,
+       array_dim_to_json(result, 0, ndim, dim, elements, nulls, &count, tcategory,
                                          typoutputfunc, use_line_feeds);
 
        pfree(elements);
@@ -908,7 +910,7 @@ composite_to_json(Datum composite, StringInfo result, bool use_line_feeds)
                else
                        val = origval;
 
-               datum_to_json(val, result, tcategory, typoutput);
+               datum_to_json(val, isnull, result, tcategory, typoutput);
 
                /* Clean up detoasted copy, if any */
                if (val != origval)