SQL/JSON: Fix casting for integer EXISTS columns in JSON_TABLE

The current method of coercing the boolean result value of
JsonPathExists() to the target type specified for an EXISTS column,
which is to call the type's input function via json_populate_type(),
leads to an error when the target type is integer, because the
integer input function doesn't recognize boolean literal values as
valid.

Instead use the boolean-to-integer cast function for coercion in that
case so that using integer or domains thereof as type for EXISTS
columns works. Note that coercion for ON ERROR values TRUE and FALSE
already works like that because the parser creates a cast expression
including the cast function, but the coercion of the actual result
value is not handled by the parser.

Tests by Jian He.

Reported-by: Jian He <[email protected]>
Author: Jian He <[email protected]>
Author: Amit Langote <[email protected]>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17

diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index f1caf48036b13482247ee330e28815d5e422a4db..9b52bab52fcb0fc03078f07f7cd589be42957365 100644 (file)
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -93,6 +93,7 @@ static void ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
                             ExprEvalStep *scratch);
 static void ExecInitJsonCoercion(ExprState *state, JsonReturning *returning,
                                 ErrorSaveContext *escontext, bool omit_quotes,
+                                bool exists_coerce,
                                 Datum *resv, bool *resnull);
 
 
@@ -4329,7 +4330,9 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
        jsestate->jump_eval_coercion = state->steps_len;
 
        ExecInitJsonCoercion(state, jsexpr->returning, escontext,
-                            jsexpr->omit_quotes, resv, resnull);
+                            jsexpr->omit_quotes,
+                            jsexpr->op == JSON_EXISTS_OP,
+                            resv, resnull);
    }
    else if (jsexpr->use_io_coercion)
    {
@@ -4410,7 +4413,8 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
        /* Step to coerce the ON ERROR expression if needed */
        if (jsexpr->on_error->coerce)
            ExecInitJsonCoercion(state, jsexpr->returning, escontext,
-                                jsexpr->omit_quotes, resv, resnull);
+                                jsexpr->omit_quotes, false,
+                                resv, resnull);
 
        /*
         * Add a COERCION_FINISH step to check for errors that may occur when
@@ -4466,7 +4470,8 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
        /* Step to coerce the ON EMPTY expression if needed */
        if (jsexpr->on_empty->coerce)
            ExecInitJsonCoercion(state, jsexpr->returning, escontext,
-                                jsexpr->omit_quotes, resv, resnull);
+                                jsexpr->omit_quotes, false,
+                                resv, resnull);
 
        /*
         * Add a COERCION_FINISH step to check for errors that may occur when
@@ -4502,6 +4507,7 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
 static void
 ExecInitJsonCoercion(ExprState *state, JsonReturning *returning,
                     ErrorSaveContext *escontext, bool omit_quotes,
+                    bool exists_coerce,
                     Datum *resv, bool *resnull)
 {
    ExprEvalStep scratch = {0};
@@ -4512,8 +4518,13 @@ ExecInitJsonCoercion(ExprState *state, JsonReturning *returning,
    scratch.resnull = resnull;
    scratch.d.jsonexpr_coercion.targettype = returning->typid;
    scratch.d.jsonexpr_coercion.targettypmod = returning->typmod;
-   scratch.d.jsonexpr_coercion.json_populate_type_cache = NULL;
+   scratch.d.jsonexpr_coercion.json_coercion_cache = NULL;
    scratch.d.jsonexpr_coercion.escontext = escontext;
    scratch.d.jsonexpr_coercion.omit_quotes = omit_quotes;
+   scratch.d.jsonexpr_coercion.exists_coerce = exists_coerce;
+   scratch.d.jsonexpr_coercion.exists_cast_to_int = exists_coerce &&
+       getBaseType(returning->typid) == INT4OID;
+   scratch.d.jsonexpr_coercion.exists_check_domain = exists_coerce &&
+       DomainHasConstraints(returning->typid);
    ExprEvalPushStep(state, &scratch);
 }

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 430438f668e4ab6061d724339c1ae71168b68e84..1633ea8373161627366f030ef4825216c69112da 100644 (file)
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -4303,13 +4303,7 @@ ExecEvalJsonExprPath(ExprState *state, ExprEvalStep *op,
                if (!error)
                {
                    *op->resnull = false;
-                   if (jsexpr->use_json_coercion)
-                       *op->resvalue = DirectFunctionCall1(jsonb_in,
-                                                           BoolGetDatum(exists) ?
-                                                           CStringGetDatum("true") :
-                                                           CStringGetDatum("false"));
-                   else
-                       *op->resvalue = BoolGetDatum(exists);
+                   *op->resvalue = BoolGetDatum(exists);
                }
            }
            break;
@@ -4550,10 +4544,46 @@ ExecEvalJsonCoercion(ExprState *state, ExprEvalStep *op,
 {
    ErrorSaveContext *escontext = op->d.jsonexpr_coercion.escontext;
 
+   /*
+    * Prepare to call json_populate_type() to coerce the boolean result of
+    * JSON_EXISTS_OP to the target type.  If the the target type is integer
+    * or a domain over integer, call the boolean-to-integer cast function
+    * instead, because the integer's input function (which is what
+    * json_populate_type() calls to coerce to scalar target types) doesn't
+    * accept boolean literals as valid input.  We only have a special case
+    * for integer and domains thereof as it seems common to use those types
+    * for EXISTS columns in JSON_TABLE().
+    */
+   if (op->d.jsonexpr_coercion.exists_coerce)
+   {
+       if (op->d.jsonexpr_coercion.exists_cast_to_int)
+       {
+           /* Check domain constraints if any. */
+           if (op->d.jsonexpr_coercion.exists_check_domain &&
+               !domain_check_safe(*op->resvalue, *op->resnull,
+                                  op->d.jsonexpr_coercion.targettype,
+                                  &op->d.jsonexpr_coercion.json_coercion_cache,
+                                  econtext->ecxt_per_query_memory,
+                                  (Node *) escontext))
+           {
+               *op->resnull = true;
+               *op->resvalue = (Datum) 0;
+           }
+           else
+               *op->resvalue = DirectFunctionCall1(bool_int4, *op->resvalue);
+           return;
+       }
+
+       *op->resvalue = DirectFunctionCall1(jsonb_in,
+                                           DatumGetBool(*op->resvalue) ?
+                                           CStringGetDatum("true") :
+                                           CStringGetDatum("false"));
+   }
+
    *op->resvalue = json_populate_type(*op->resvalue, JSONBOID,
                                       op->d.jsonexpr_coercion.targettype,
                                       op->d.jsonexpr_coercion.targettypmod,
-                                      &op->d.jsonexpr_coercion.json_populate_type_cache,
+                                      &op->d.jsonexpr_coercion.json_coercion_cache,
                                       econtext->ecxt_per_query_memory,
                                       op->resnull,
                                       op->d.jsonexpr_coercion.omit_quotes,

diff --git a/src/include/executor/execExpr.h b/src/include/executor/execExpr.h
index 55337d49166f671243ce5a8c6842e1b8614e700f..d983a9a7fed8f87ac7b924fc4f942c910bc98612 100644 (file)
--- a/src/include/executor/execExpr.h
+++ b/src/include/executor/execExpr.h
@@ -708,7 +708,11 @@ typedef struct ExprEvalStep
            Oid         targettype;
            int32       targettypmod;
            bool        omit_quotes;
-           void       *json_populate_type_cache;
+           /* exists_* fields only relevant for JSON_EXISTS_OP. */
+           bool        exists_coerce;
+           bool        exists_cast_to_int;
+           bool        exists_check_domain;
+           void       *json_coercion_cache;
            ErrorSaveContext *escontext;
        }           jsonexpr_coercion;
    }           d;

diff --git a/src/test/regress/expected/sqljson_jsontable.out b/src/test/regress/expected/sqljson_jsontable.out
index 24892d5e18a88caca0f5da7ddce795c9901570b8..9a97dd90d787f122b6d5e44b37999b74f7082263 100644 (file)
--- a/src/test/regress/expected/sqljson_jsontable.out
+++ b/src/test/regress/expected/sqljson_jsontable.out
@@ -175,7 +175,7 @@ FROM json_table_test vals
  [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] |  6 | f       |       0 |         | false
  [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] |  7 | f       |       0 |         | false
  [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] |  8 | f       |       0 |         | false
- [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] |  9 | t       |       0 |         | true
+ [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] |  9 | t       |       1 |       1 | true
  [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] | 10 | f       |       0 |         | false
  [1, 1.23, "2", "aaaaaaa", "foo", null, false, true, {"aaa": 123}, "[1,2]", "\"str\""] | 11 | f       |       0 |         | false
 (14 rows)
@@ -549,12 +549,18 @@ SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int PATH 'lax $.a' DEFAULT
 (1 row)
 
 -- JSON_TABLE: EXISTS PATH types
-SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$.a'));
+SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$.a' ERROR ON ERROR));  -- ok; can cast to int4
  a 
 ---
  0
 (1 row)
 
+SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$' ERROR ON ERROR));    -- ok; can cast to int4
+ a 
+---
+ 1
+(1 row)
+
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int2 EXISTS PATH '$.a'));
 ERROR:  could not coerce ON ERROR expression (FALSE) to the RETURNING type
 DETAIL:  invalid input syntax for type smallint: "false"
@@ -588,6 +594,30 @@ SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a jsonb EXISTS PATH '$.a'));
  false
 (1 row)
 
+-- EXISTS PATH domain over int
+CREATE DOMAIN dint4 AS int;
+CREATE DOMAIN dint4_0 AS int CHECK (VALUE <> 0 );
+SELECT a, a::bool FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a dint4 EXISTS PATH '$.a' ));
+ a | a 
+---+---
+ 0 | f
+(1 row)
+
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b'));
+ERROR:  could not coerce ON ERROR expression (FALSE) to the RETURNING type
+DETAIL:  value for domain dint4_0 violates check constraint "dint4_0_check"
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' ERROR ON ERROR));
+ERROR:  value for domain dint4_0 violates check constraint "dint4_0_check"
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' FALSE ON ERROR));
+ERROR:  could not coerce ON ERROR expression (FALSE) to the RETURNING type
+DETAIL:  value for domain dint4_0 violates check constraint "dint4_0_check"
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' TRUE ON ERROR));
+ a | a 
+---+---
+ 1 | t
+(1 row)
+
+DROP DOMAIN dint4, dint4_0;
 -- JSON_TABLE: WRAPPER/QUOTES clauses on scalar columns
 SELECT * FROM JSON_TABLE(jsonb '"world"', '$' COLUMNS (item text PATH '$' KEEP QUOTES ON SCALAR STRING));
   item   

diff --git a/src/test/regress/sql/sqljson_jsontable.sql b/src/test/regress/sql/sqljson_jsontable.sql
index dc509bed8afc12272fd05e9b68c2b6fb5850fbcd..38992316f5afeb28947bce8879840364e9895e16 100644 (file)
--- a/src/test/regress/sql/sqljson_jsontable.sql
+++ b/src/test/regress/sql/sqljson_jsontable.sql
@@ -262,7 +262,8 @@ SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int PATH 'strict $.a' DEFAU
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int PATH 'lax $.a' DEFAULT 1 ON EMPTY DEFAULT 2 ON ERROR)) jt;
 
 -- JSON_TABLE: EXISTS PATH types
-SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$.a'));
+SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$.a' ERROR ON ERROR));  -- ok; can cast to int4
+SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int4 EXISTS PATH '$' ERROR ON ERROR));    -- ok; can cast to int4
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int2 EXISTS PATH '$.a'));
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a int8 EXISTS PATH '$.a'));
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a float4 EXISTS PATH '$.a'));
@@ -273,6 +274,16 @@ SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a char(5) EXISTS PATH '$.a' E
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a json EXISTS PATH '$.a'));
 SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a jsonb EXISTS PATH '$.a'));
 
+-- EXISTS PATH domain over int
+CREATE DOMAIN dint4 AS int;
+CREATE DOMAIN dint4_0 AS int CHECK (VALUE <> 0 );
+SELECT a, a::bool FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a dint4 EXISTS PATH '$.a' ));
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b'));
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' ERROR ON ERROR));
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' FALSE ON ERROR));
+SELECT a, a::bool FROM JSON_TABLE(jsonb '{"a":1}', '$' COLUMNS (a dint4_0 EXISTS PATH '$.b' TRUE ON ERROR));
+DROP DOMAIN dint4, dint4_0;
+
 -- JSON_TABLE: WRAPPER/QUOTES clauses on scalar columns
 SELECT * FROM JSON_TABLE(jsonb '"world"', '$' COLUMNS (item text PATH '$' KEEP QUOTES ON SCALAR STRING));
 SELECT * FROM JSON_TABLE(jsonb '"world"', '$' COLUMNS (item text PATH '$' OMIT QUOTES ON SCALAR STRING));