Am Montag, 2. April 2007 18:41 schrieb Tom Lane:
> >> The scheme that was in the back of my mind was to do this at the same
> >> time as providing a general facility for casting *every* type to and
> >> from text, by means of their I/O functions if no specialized cast is
> >> provided in pg_cast.
> http://archives.postgresql.org/pgsql-admin/2004-06/msg00390.php
> http://archives.postgresql.org/pgsql-hackers/2004-10/msg00303.php
FWIW, is the attached patch about what you had in mind? (It probably only
covers "normal" types at the moment.)
--
Peter Eisentraut
http://developer.postgresql.org/~petere/
diff -ur ../cvs-pgsql/src/backend/parser/parse_coerce.c ./src/backend/parser/parse_coerce.c
--- ../cvs-pgsql/src/backend/parser/parse_coerce.c 2007-04-02 08:52:16.000000000 +0200
+++ ./src/backend/parser/parse_coerce.c 2007-04-03 18:05:12.000000000 +0200
@@ -371,6 +371,28 @@
r->convertformat = cformat;
return (Node *) r;
}
+ if ((inputTypeId == TEXTOID || targetTypeId == TEXTOID) && ccontext == COERCION_EXPLICIT)
+ {
+ /* Explicit coercion through I/O functions */
+ Oid inputTypeOutput;
+ Oid targetTypeInput;
+ bool isVarlena;
+ Oid typeIOParam;
+
+ getTypeInputInfo(targetTypeId, &targetTypeInput, &typeIOParam);
+ getTypeOutputInfo(inputTypeId, &inputTypeOutput, &isVarlena);
+
+ result = build_coercion_expression(build_coercion_expression(node, inputTypeOutput, arrayCoerce,
+ CSTRINGOID, -1,
+ cformat,
+ (cformat != COERCE_IMPLICIT_CAST)),
+ targetTypeInput, arrayCoerce,
+ targetTypeId, -1,
+ cformat,
+ (cformat != COERCE_IMPLICIT_CAST));
+
+ return result;
+ }
/* If we get here, caller blew it */
elog(ERROR, "failed to find conversion function from %s to %s",
format_type_be(inputTypeId), format_type_be(targetTypeId));
@@ -451,6 +473,10 @@
if (typeInheritsFrom(inputTypeId, targetTypeId))
continue;
+ /* Else only explicit coercion from/to text is possible through I/O functions */
+ if ((inputTypeId == TEXTOID || targetTypeId == TEXTOID) && ccontext == COERCION_EXPLICIT)
+ continue;
+
/*
* Else, cannot coerce at this argument position
*/
---------------------------(end of broadcast)---------------------------
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