Re: remaining sql/json patches

On Wed, Dec 6, 2023 at 10:02 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
>
> Finally, I also fixed a couple of silly mistakes in 0003 around
> transformJsonBehavior() and some further assorted tightening in the ON
> ERROR / EMPTY expression coercion handling code.
>

typo:
+ * If a soft-error occurs, it will be checked by EEOP_JSONEXPR_COECION_FINISH

json_exists no RETURNING clause.
so the following part in src/backend/parser/parse_expr.c can be removed?

+ else if (jsexpr->returning->typid != BOOLOID)
+ {
+ Node *coercion_expr;
+ CaseTestExpr *placeholder = makeNode(CaseTestExpr);
+ int location = exprLocation((Node *) jsexpr);
+
+ /*
+ * We abuse CaseTestExpr here as placeholder to pass the
+ * result of evaluating JSON_EXISTS to the coercion
+ * expression.
+ */
+ placeholder->typeId = BOOLOID;
+ placeholder->typeMod = -1;
+ placeholder->collation = InvalidOid;
+
+ coercion_expr =
+ coerce_to_target_type(pstate, (Node *) placeholder, BOOLOID,
+ jsexpr->returning->typid,
+ jsexpr->returning->typmod,
+ COERCION_EXPLICIT,
+ COERCE_IMPLICIT_CAST,
+ location);
+
+ if (coercion_expr == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_CANNOT_COERCE),
+ errmsg("cannot cast type %s to %s",
+ format_type_be(BOOLOID),
+ format_type_be(jsexpr->returning->typid)),
+ parser_coercion_errposition(pstate, location, (Node *) jsexpr)));
+
+ if (coercion_expr != (Node *) placeholder)
+ jsexpr->result_coercion = coercion_expr;
+ }

Similarly, since JSON_EXISTS has no RETURNING clause, the following
also needs to be refactored?

+ /*
+ * Disallow FORMAT specification in the RETURNING clause of JSON_EXISTS()
+ * and JSON_VALUE().
+ */
+ if (func->output &&
+ (func->op == JSON_VALUE_OP || func->op == JSON_EXISTS_OP))
+ {
+ JsonFormat *format = func->output->returning->format;
+
+ if (format->format_type != JS_FORMAT_DEFAULT ||
+ format->encoding != JS_ENC_DEFAULT)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("cannot specify FORMAT in RETURNING clause of %s",
+ func->op == JSON_VALUE_OP ? "JSON_VALUE()" :
+ "JSON_EXISTS()"),
+ parser_errposition(pstate, format->location)));