plpgsql errorcodes

hi,

i want the DB functionality to be done by the server. this means i want to 
write functions like

CREATE FUNCTION insert_any(....) RETURNS INT AS '
BEGIN

END; '
LANGUAGE 'plpgsql'

returning an errorcode so i can map this errorcode to a message for the user 
of the client. and i want to do this on the server without  using any 
special java or php command on the client side.

the only  thing postgreSQL returns - if an error occured - is a textual 
message you cant use for telling the user what happend.

one thing i want to know - inside the function - is  why postgre stopped 
working. something like
 num := CAST($1 AS INT); IF ERROR THEN RETURN -3; END IF;  -- "cannot convert to integer"

because i do not want to reenvent the wheel. if there is a conversion 
function i want to use it, and i want to know if or why it failed.

besides i have written simple type checking functions doing the following

// php

$ret = pg_call("SELECT checkInteger('abc')"); if ($ret != 0) $msg = pg_call("SELECT getErrorMessage($ret,'german')");
else...
 

i can use the same functions in every client program (java, VB, C ..).
but i think it is absurd to do the same thing twice. postgre checks it also 
in the CAST
statement. the only thing i want to know is what happend.  even a parseable 
errorcode
like

ERROR(23890) : 'invalid numeric format'

or

ERROR(100) constraint 'myConstraintName '

would be helpfull

is there ANY possibility to catch errorcodes in plpqsql ?
is there ANY possibility to catch errorcodes otherwise ?

i am using postgreSQL 7.4

thanx

Sepp

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