Hate to reply to my own posts, but I thought the solution I've come
across may help others with problems implementing savepoints and
transactions in functions.
This function implements rollbacks whilst still returning a valid row
instead of an exception. A temporary variable is used to get around the
ugly lack of SAVEPOINTs.
----------------------------------------------------------------------
CREATE OR REPLACE FUNCTION tr_addcoursearea(employeeno, coursearea) RETURNS int4 AS
$BODY$DECLARE transid int4; errcode int4;
BEGIN -- Setup default return code. This is used if we hit an -- exception that we didn't throw. SELECT -32767 into
errcode; -- E_UNKNOWN
LOCK TABLE backend.courseareas IN ACCESS EXCLUSIVE MODE;
-- Access to administrators only IF NOT tt_user_access(actor, 'a') THEN SELECT -1 into errcode; -- Return
E_NO_ACCESS RAISE EXCEPTION 'User % does not have access.', actor; END IF;
-- Check if there are any active course areas with -- the given name. We do not allow duplicate names.. -- confusion
mayabound. IF tt_coursearea_name_active(area) THEN SELECT -2001 INTO errcode; -- E_DUP_COURSEAREA RAISE EXCEPTION
'Coursearea "%" already exists.', area; END IF;
-- Grab a transaction ID SELECT tt_acquire_transaction(actor, 'tr_addcourse') INTO transid; IF transid < 0 THEN
SELECTtransid into errcode; -- Return the error code. RAISE EXCEPTION 'Could not acquire transaction.'; END IF;
-- Insert the row INSERT INTO backend.courseareas (transactionid, active, caname) VALUES (transid, TRUE, area);
RETURN 0; -- SUCCESS
EXCEPTION WHEN RAISE_EXCEPTION THEN RETURN errcode;
WHEN OTHERS THEN RETURN -32767; -- E_UNKNOWN
END;$BODY$ LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER;
----------------------------------------------------------------------
Best regards,
Ben Stewart
--
Robert Bosch (Australia) Pty. Ltd.
Engineering Quality Services, Student Software Engineer (RBAU/EQS4)
Locked Bag 66 - Clayton South, VIC 3169 - AUSTRALIA
mailto:ben.stewart@au.bosch.com
http://www.bosch.com.au/
