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SQL/JSON: Fix issues with DEFAULT .. ON ERROR / EMPTY 

SQL/JSON query functions allow specifying an expression to return
when either of ON ERROR or ON EMPTY condition occurs when evaluating
the JSON path expression.  The parser (transformJsonBehavior()) checks
that the specified expression is one of the supported expressions, but
there are two issues with how the check is done that are fixed in this
commit:

* No check for some expressions related to coercion, such as
  CoerceViaIO, that may appear in the transformed user-specified
  expressions that include cast(s)

* An unsupported expression may be masked by a coercion-related
  expression, which must be flagged by checking the latter's
  argument expression recursively

Author: Jian He <jian.universality@gmail.com>
Author: Amit Langote <amitlangote09@gmail.com>
Reported-by: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEqhqsfrg_p7EMyo5zak3d767iFDL8vz_4%3DZBHpOtrghw@mail.gmail.com
Discussion: https://postgr.es/m/CACJufxGOerH1QJknm1noh-Kz5FqU4p7QfeZSeVT2tN_4SLXYNg@mail.gmail.com
This commit is contained in:
Amit Langote 2024-04-18 14:46:35 +09:00
parent b4fad46b6b
commit c0fc075186
5 changed files with 167 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
src/backend/parser/parse_expr.c
View File

@ -4616,6 +4616,40 @@ coerceJsonExprOutput(ParseState *pstate, JsonExpr *jsexpr)
(jsexpr->use_io_coercion != jsexpr->use_json_coercion));
}
/*
* Recursively checks if the given expression, or its sub-node in some cases,
* is valid for using as an ON ERROR / ON EMPTY DEFAULT expression.
*/
static bool
ValidJsonBehaviorDefaultExpr(Node *expr, void *context)
{
if (expr == NULL)
return false;
switch (nodeTag(expr))
{
/* Acceptable expression nodes */
case T_Const:
case T_FuncExpr:
case T_OpExpr:
return true;
/* Acceptable iff arg of the following nodes is one of the above */
case T_CoerceViaIO:
case T_CoerceToDomain:
case T_ArrayCoerceExpr:
case T_ConvertRowtypeExpr:
case T_RelabelType:
case T_CollateExpr:
return expression_tree_walker(expr, ValidJsonBehaviorDefaultExpr,
context);
default:
break;
}
return false;
}
/*
* Transform a JSON BEHAVIOR clause.
*/
@ -4636,8 +4670,7 @@ transformJsonBehavior(ParseState *pstate, JsonBehavior *behavior,
if (btype == JSON_BEHAVIOR_DEFAULT)
{
expr = transformExprRecurse(pstate, behavior->expr);
if (!IsA(expr, Const) && !IsA(expr, FuncExpr) &&
!IsA(expr, OpExpr))
if (!ValidJsonBehaviorDefaultExpr(expr, NULL))
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("can only specify a constant, non-aggregate function, or operator expression for DEFAULT"),

32
src/test/regress/expected/sqljson_jsontable.out
View File

@ -217,6 +217,38 @@ FROM json_table_test vals
[1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] | 11 | | | "\"str\"" | ["\"str\""] | "str" | | |
(14 rows)
-- 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));
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));
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));
js1
------
foo1
(1 row)
SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
COLUMNS (js1 jsonb_test_domain PATH '$.d1' DEFAULT 'foo2'::jsonb_test_domain ON ERROR));
js1
------
foo2
(1 row)
SELECT * FROM JSON_TABLE(jsonb '{"d1": "foo"}', '$'
COLUMNS (js1 oid[] PATH '$.d2' DEFAULT '{1}'::int[]::oid[] ON ERROR));
js1
-----
{1}
(1 row)
-- JSON_TABLE: Test backward parsing
CREATE VIEW jsonb_table_view2 AS
SELECT * FROM

57
src/test/regress/expected/sqljson_queryfuncs.out
View File

@ -1222,6 +1222,63 @@ LINE 1: SELECT JSON_QUERY(js, '$' RETURNING int DEFAULT (SELECT 1) ...
^
DROP TABLE test_jsonb_mutability;
DROP FUNCTION ret_setint;
CREATE DOMAIN jsonb_test_domain AS text CHECK (value <> 'foo');
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo'::jsonb_test_domain ON ERROR);
ERROR: value for domain jsonb_test_domain violates check constraint "jsonb_test_domain_check"
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo1'::jsonb_test_domain ON ERROR);
json_value
------------
foo1
(1 row)
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT '"foo1"'::jsonb::text ON ERROR);
json_value
------------
"foo1"
(1 row)
SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo1'::jsonb_test_domain ON ERROR);
json_value
------------
foo1
(1 row)
-- Check the cases where a coercion-related expression is masking an
-- unsupported expressions
-- CoerceViaIO
SELECT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT '"1"')::jsonb ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ...CT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT '"...
^
-- CoerceToDomain
SELECT JSON_QUERY('"a"', '$.a' RETURNING jsonb_test_domain DEFAULT (select '"1"')::jsonb_test_domain ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ...('"a"', '$.a' RETURNING jsonb_test_domain DEFAULT (select '"...
^
-- RelabelType
SELECT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT 1)::oid::int ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ...CT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT 1)...
^
-- ArrayCoerceExpr
SELECT JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{1}')::oid[]::int[] ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ... JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{...
^
-- CollateExpr
SELECT JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{1}')::text COLLATE "C" ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ... JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{...
^
-- ConvertRowtypeExpr
CREATE TABLE someparent (a int);
CREATE TABLE somechild () INHERITS (someparent);
SELECT JSON_QUERY('"a"', '$.a' RETURNING someparent DEFAULT (SELECT '(1)')::somechild::someparent ON ERROR);
ERROR: can only specify a constant, non-aggregate function, or operator expression for DEFAULT
LINE 1: ..._QUERY('"a"', '$.a' RETURNING someparent DEFAULT (SELECT '(...
^
DROP DOMAIN jsonb_test_domain;
DROP TABLE someparent, somechild;
-- Extension: non-constant JSON path
SELECT JSON_EXISTS(jsonb '{"a": 123}', '$' || '.' || 'a');
json_exists

16
src/test/regress/sql/sqljson_jsontable.sql
View File

@ -116,6 +116,22 @@ FROM json_table_test vals
) jt
ON true;
-- 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));
SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo'::jsonb_test_domain ON ERROR));
SELECT * FROM JSON_TABLE(jsonb '{"d1": "H"}', '$'
COLUMNS (js1 jsonb_test_domain PATH '$.a2' DEFAULT 'foo1'::jsonb_test_domain ON ERROR));
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));
-- JSON_TABLE: Test backward parsing
CREATE VIEW jsonb_table_view2 AS

27
src/test/regress/sql/sqljson_queryfuncs.sql
View File

@ -411,6 +411,33 @@ SELECT JSON_QUERY(js, '$' RETURNING int DEFAULT (SELECT 1) ON ERROR) FROM test_
DROP TABLE test_jsonb_mutability;
DROP FUNCTION ret_setint;
CREATE DOMAIN jsonb_test_domain AS text CHECK (value <> 'foo');
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo'::jsonb_test_domain ON ERROR);
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo1'::jsonb_test_domain ON ERROR);
SELECT JSON_VALUE(jsonb '{"d1": "H"}', '$.a2' RETURNING jsonb_test_domain DEFAULT '"foo1"'::jsonb::text ON ERROR);
SELECT JSON_VALUE(jsonb '{"d1": "foo"}', '$.a2' RETURNING jsonb_test_domain DEFAULT 'foo1'::jsonb_test_domain ON ERROR);
-- Check the cases where a coercion-related expression is masking an
-- unsupported expressions
-- CoerceViaIO
SELECT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT '"1"')::jsonb ON ERROR);
-- CoerceToDomain
SELECT JSON_QUERY('"a"', '$.a' RETURNING jsonb_test_domain DEFAULT (select '"1"')::jsonb_test_domain ON ERROR);
-- RelabelType
SELECT JSON_QUERY('"a"', '$.a' RETURNING int DEFAULT (SELECT 1)::oid::int ON ERROR);
-- ArrayCoerceExpr
SELECT JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{1}')::oid[]::int[] ON ERROR);
-- CollateExpr
SELECT JSON_QUERY('"a"', '$.a' RETURNING int[] DEFAULT (SELECT '{1}')::text COLLATE "C" ON ERROR);
-- ConvertRowtypeExpr
CREATE TABLE someparent (a int);
CREATE TABLE somechild () INHERITS (someparent);
SELECT JSON_QUERY('"a"', '$.a' RETURNING someparent DEFAULT (SELECT '(1)')::somechild::someparent ON ERROR);
DROP DOMAIN jsonb_test_domain;
DROP TABLE someparent, somechild;
-- Extension: non-constant JSON path
SELECT JSON_EXISTS(jsonb '{"a": 123}', '$' || '.' || 'a');
SELECT JSON_VALUE(jsonb '{"a": 123}', '$' || '.' || 'a');