SQL/JSON: Correctly enforce the default ON EMPTY behavior

Currently, when the ON EMPTY clause is not present, the ON ERROR
clause (implicit or explicit) dictates the behavior when jsonpath
evaluation in ExecEvalJsonExprPath() results in an empty sequence.
That is an oversight in the commit 6185c9737c.

This commit fixes things so that a NULL is returned instead in that
case which is the default behavior when the ON EMPTY clause is not
present.

Reported-by: Markus Winand
Discussion: https://postgr.es/m/F7DD1442-265C-4220-A603-CB0DEB77E91D%40winand.at

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 4c95986c312d83b47c62a051647c3b6726a7ff87..00cd7358ebbe83a48bc38280bca92cd8dfe2974f 100644 (file)
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -4418,11 +4418,11 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
 
            coerceJsonExprOutput(pstate, jsexpr);
 
-           if (func->on_empty)
-               jsexpr->on_empty = transformJsonBehavior(pstate,
-                                                        func->on_empty,
-                                                        JSON_BEHAVIOR_NULL,
-                                                        jsexpr->returning);
+           /* Assume NULL ON EMPTY when ON EMPTY is not specified. */
+           jsexpr->on_empty = transformJsonBehavior(pstate, func->on_empty,
+                                                    JSON_BEHAVIOR_NULL,
+                                                    jsexpr->returning);
+           /* Assume NULL ON ERROR when ON ERROR is not specified. */
            jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
                                                     JSON_BEHAVIOR_NULL,
                                                     jsexpr->returning);
@@ -4448,11 +4448,11 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
 
            coerceJsonExprOutput(pstate, jsexpr);
 
-           if (func->on_empty)
-               jsexpr->on_empty = transformJsonBehavior(pstate,
-                                                        func->on_empty,
-                                                        JSON_BEHAVIOR_NULL,
-                                                        jsexpr->returning);
+           /* Assume NULL ON EMPTY when ON EMPTY is not specified. */
+           jsexpr->on_empty = transformJsonBehavior(pstate, func->on_empty,
+                                                    JSON_BEHAVIOR_NULL,
+                                                    jsexpr->returning);
+           /* Assume NULL ON ERROR when ON ERROR is not specified. */
            jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
                                                     JSON_BEHAVIOR_NULL,
                                                     jsexpr->returning);
@@ -4464,6 +4464,13 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
                jsexpr->returning->typid = exprType(jsexpr->formatted_expr);
                jsexpr->returning->typmod = -1;
            }
+
+           /*
+            * Assume EMPTY ON ERROR when ON ERROR is not specified.
+            *
+            * ON EMPTY cannot be specified at the top level but it can be for
+            * the individual columns.
+            */
            jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
                                                     JSON_BEHAVIOR_EMPTY,
                                                     jsexpr->returning);

diff --git a/src/test/regress/expected/sqljson_jsontable.out b/src/test/regress/expected/sqljson_jsontable.out
index 9f649483cecf729ec39852dc000a9b4d425a55b7..cee90cead13b6c46a56ddfb879c9322b28e78a85 100644 (file)
--- a/src/test/regress/expected/sqljson_jsontable.out
+++ b/src/test/regress/expected/sqljson_jsontable.out
@@ -219,17 +219,17 @@ FROM json_table_test vals
 
 -- Test using casts in DEFAULT .. ON ERROR expression
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT '"foo1"'::jsonb::text ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT '"foo1"'::jsonb::text ON EMPTY));
   js1   
 --------
  "foo1"
 (1 row)
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo'::jsonb_test_domain ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo'::jsonb_test_domain ON EMPTY));
 ERROR:  value for domain jsonb_test_domain violates check constraint "jsonb_test_domain_check"
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo1'::jsonb_test_domain ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo1'::jsonb_test_domain ON EMPTY));
  js1  
 ------
  foo1
@@ -243,7 +243,7 @@ SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
 (1 row)
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
-    COLUMNS (js1 oid[] PATH '$.d2' DEFAULT '{1}'::int[]::oid[] ON ERROR));
+    COLUMNS (js1 oid[] PATH '$.d2' DEFAULT '{1}'::int[]::oid[] ON EMPTY));
  js1 
 -----
  {1}
@@ -885,7 +885,16 @@ SELECT sub.* FROM s,
        xx int path '$.c',
        NESTED PATH '$.a.za[1]' columns (NESTED PATH '$.z21[*]' COLUMNS (z21 int path '$?(@ >= $"x")' ERROR ON ERROR))
    )) sub;
-ERROR:  no SQL/JSON item found for specified path of column "z21"
+ xx | z21  
+----+------
+  3 |     
+  3 |  234
+  3 | 2345
+ 10 |   32
+ 10 |  134
+ 10 | 1345
+(6 rows)
+
 -- Parent columns xx1, xx appear before NESTED ones
 SELECT sub.* FROM s,
    (VALUES (23)) x(x), generate_series(13, 13) y,

diff --git a/src/test/regress/expected/sqljson_queryfuncs.out b/src/test/regress/expected/sqljson_queryfuncs.out
index 98117b346d46de5d7c2b42a3ace84c418fd276c1..9cb250a27a77ae8cd9f18c7d4f32a19f15e6a0ad 100644 (file)
--- a/src/test/regress/expected/sqljson_queryfuncs.out
+++ b/src/test/regress/expected/sqljson_queryfuncs.out
@@ -362,11 +362,15 @@ SELECT JSON_VALUE(jsonb '1', 'strict $.a' DEFAULT 'error' ON ERROR);
  error
 (1 row)
 
-SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON ERROR);
-ERROR:  no SQL/JSON item found for specified path
+SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON ERROR);    -- NULL ON EMPTY
+ json_value 
+------------
+ 
+(1 row)
+
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON EMPTY ERROR ON ERROR);
 ERROR:  no SQL/JSON item found for specified path
-SELECT JSON_VALUE(jsonb '1', 'strict $.a' DEFAULT 2 ON ERROR);
+SELECT JSON_VALUE(jsonb '1', 'strict $.*' DEFAULT 2 ON ERROR);
  json_value 
 ------------
  2
@@ -375,10 +379,10 @@ SELECT JSON_VALUE(jsonb '1', 'strict $.a' DEFAULT 2 ON ERROR);
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT 2 ON ERROR);
  json_value 
 ------------
- 2
+ 
 (1 row)
 
-SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT '2' ON ERROR);
+SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT '2' ON EMPTY);
  json_value 
 ------------
  2
@@ -773,8 +777,12 @@ SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY EMPTY OBJECT ON ERROR);
 ERROR:  no SQL/JSON item found for specified path
 SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY ERROR ON ERROR);
 ERROR:  no SQL/JSON item found for specified path
-SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON ERROR);
-ERROR:  no SQL/JSON item found for specified path
+SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON ERROR);  -- NULL ON EMPTY
+ json_query 
+------------
+ 
+(1 row)
+
 SELECT JSON_QUERY(jsonb '[1,2]', '$[*]' ERROR ON ERROR);
 ERROR:  JSON path expression in JSON_QUERY should return single item without wrapper
 HINT:  Use WITH WRAPPER clause to wrap SQL/JSON items into array.
@@ -1032,7 +1040,7 @@ SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null);
            
 (1 row)
 
-SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null ERROR ON ERROR);
+SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null ERROR ON EMPTY ERROR ON ERROR);
 ERROR:  no SQL/JSON item found for specified path
 -- Test timestamptz passing and output
 SELECT JSON_QUERY(jsonb 'null', '$ts' PASSING timestamptz '2018-02-21 12:34:56 +10' AS ts);
@@ -1223,21 +1231,21 @@ LINE 1: SELECT JSON_QUERY(js, '$'  RETURNING int DEFAULT (SELECT 1) ...
 DROP TABLE test_jsonb_mutability;
 DROP FUNCTION ret_setint;
 CREATE DOMAIN queryfuncs_test_domain AS text CHECK (value <> 'foo');
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo'::queryfuncs_test_domain ON ERROR);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo'::queryfuncs_test_domain ON EMPTY);
 ERROR:  value for domain queryfuncs_test_domain violates check constraint "queryfuncs_test_domain_check"
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON ERROR);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON EMPTY);
  json_value 
 ------------
  foo1
 (1 row)
 
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT '"foo1"'::jsonb::text ON ERROR);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT '"foo1"'::jsonb::text ON EMPTY);
  json_value 
 ------------
  "foo1"
 (1 row)
 
-SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON ERROR);
+SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON EMPTY);
  json_value 
 ------------
  foo1

diff --git a/src/test/regress/sql/sqljson_jsontable.sql b/src/test/regress/sql/sqljson_jsontable.sql
index f8f996f93529a62989a0744ab08c0ecce102a0af..a1f924146e069f0e66827b11554ff3779c796805 100644 (file)
--- a/src/test/regress/sql/sqljson_jsontable.sql
+++ b/src/test/regress/sql/sqljson_jsontable.sql
@@ -118,19 +118,19 @@ FROM json_table_test vals
 
 -- Test using casts in DEFAULT .. ON ERROR expression
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT '"foo1"'::jsonb::text ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT '"foo1"'::jsonb::text ON EMPTY));
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo'::jsonb_test_domain ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo'::jsonb_test_domain ON EMPTY));
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
-    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo1'::jsonb_test_domain ON ERROR));
+    COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo1'::jsonb_test_domain ON EMPTY));
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
     COLUMNS (js1 jsonb_test_domain PATH '$.d1' DEFAULT 'foo2'::jsonb_test_domain ON ERROR));
 
 SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
-    COLUMNS (js1 oid[] PATH '$.d2' DEFAULT '{1}'::int[]::oid[] ON ERROR));
+    COLUMNS (js1 oid[] PATH '$.d2' DEFAULT '{1}'::int[]::oid[] ON EMPTY));
 
 -- JSON_TABLE: Test backward parsing
 

diff --git a/src/test/regress/sql/sqljson_queryfuncs.sql b/src/test/regress/sql/sqljson_queryfuncs.sql
index d9dbb1ceaacf02051a11a4d5e4ee300a3c48c2e8..dc6380141b862b9ff5d52f432a49ae7796118f6f 100644 (file)
--- a/src/test/regress/sql/sqljson_queryfuncs.sql
+++ b/src/test/regress/sql/sqljson_queryfuncs.sql
@@ -87,11 +87,11 @@ SELECT JSON_VALUE(jsonb '{}', '$' ERROR ON ERROR);
 SELECT JSON_VALUE(jsonb '1', '$.a');
 SELECT JSON_VALUE(jsonb '1', 'strict $.a' ERROR ON ERROR);
 SELECT JSON_VALUE(jsonb '1', 'strict $.a' DEFAULT 'error' ON ERROR);
-SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON ERROR);
+SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON ERROR);    -- NULL ON EMPTY
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON EMPTY ERROR ON ERROR);
-SELECT JSON_VALUE(jsonb '1', 'strict $.a' DEFAULT 2 ON ERROR);
+SELECT JSON_VALUE(jsonb '1', 'strict $.*' DEFAULT 2 ON ERROR);
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT 2 ON ERROR);
-SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT '2' ON ERROR);
+SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT '2' ON EMPTY);
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' NULL ON EMPTY DEFAULT '2' ON ERROR);
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' DEFAULT '2' ON EMPTY DEFAULT '3' ON ERROR);
 SELECT JSON_VALUE(jsonb '1', 'lax $.a' ERROR ON EMPTY DEFAULT '3' ON ERROR);
@@ -224,7 +224,7 @@ SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY NULL ON ERROR);
 SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY EMPTY ARRAY ON ERROR);
 SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY EMPTY OBJECT ON ERROR);
 SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON EMPTY ERROR ON ERROR);
-SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON ERROR);
+SELECT JSON_QUERY(jsonb '[]', '$[*]' ERROR ON ERROR);  -- NULL ON EMPTY
 
 SELECT JSON_QUERY(jsonb '[1,2]', '$[*]' ERROR ON ERROR);
 SELECT JSON_QUERY(jsonb '[1,2]', '$[*]' DEFAULT '"empty"' ON ERROR);
@@ -304,7 +304,7 @@ SELECT * FROM unnest(JSON_QUERY(jsonb '[{"a": 1, "t": ["foo", []]}, {"a": 2, "jb
 -- Extension: domain types returning
 SELECT JSON_QUERY(jsonb '{"a": 1}', '$.a' RETURNING sqljsonb_int_not_null);
 SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null);
-SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null ERROR ON ERROR);
+SELECT JSON_QUERY(jsonb '{"a": 1}', '$.b' RETURNING sqljsonb_int_not_null ERROR ON EMPTY ERROR ON ERROR);
 
 -- Test timestamptz passing and output
 SELECT JSON_QUERY(jsonb 'null', '$ts' PASSING timestamptz '2018-02-21 12:34:56 +10' AS ts);
@@ -412,10 +412,10 @@ DROP TABLE test_jsonb_mutability;
 DROP FUNCTION ret_setint;
 
 CREATE DOMAIN queryfuncs_test_domain AS text CHECK (value <> 'foo');
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo'::queryfuncs_test_domain ON ERROR);
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON ERROR);
-SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT '"foo1"'::jsonb::text ON ERROR);
-SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON ERROR);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo'::queryfuncs_test_domain ON EMPTY);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON EMPTY);
+SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT '"foo1"'::jsonb::text ON EMPTY);
+SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING queryfuncs_test_domain DEFAULT 'foo1'::queryfuncs_test_domain ON EMPTY);
 
 -- Check the cases where a coercion-related expression is masking an
 -- unsupported expressions