CREATE SCHEMA altschema;
CREATE TYPE altschema.alttype AS ( altid text, altlabel text );
CREATE FUNCTION altschema.label(item altschema.alttype)
RETURNS text
LANGUAGE sql
AS $$
SELECT (item).altlabel;
$$;
WITH vals (v) AS (
SELECT ('1', 'One')::altschema.alttype
)
SELECT (v).label
FROM vals;
-- column "label" not found in data type altschema.alttype
SET search_path TO altschema;
WITH vals (v) AS (
SELECT ('1', 'One')::altschema.alttype
)
SELECT (v).label
FROM vals;
-- success
The system knows that the datatype being inspected is "altschema.alttype" - would it be reasonable for the system to check for a function named "label" in the same schema as the target type, "altschema", with the target argument type and invoke it if present?
At this point I'm just writing: altschema.label(v) which is adequate but not as clean. I'm consciously trying to write queries that don't require application schemas in the search path: including the joyous operator(altschema.@@) syntax in some situations. I suppose inference could be considered in that situation as well.
David J.