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Re: How return a row from a function so it is recognized as such by caller?

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On Wed, Mar 28, 2012 at 1:52 PM, Kenneth Tilton <ktilton@xxxxxxxx> wrote:
First, apologies for being too succinct. I should have reiterated the message subject to provide the context: I am just trying to return a row from a function and have the caller understand it. Oh, and I am a nooby so it is probably something daft.

Second, I just tried returning the row as an out variable and got the same result. I'll try messing with the caller...

OK, this works in re getting the row back:

    bpa := now_plus_30(NEW);

But I need to execute an arbitrary function passed in as text, and I now realize EXECUTE is for SQL and I am trying to use it to "eval" plpgsql and those are different animals.

I see no plpgsql equivalent of EXECUTE, ie where I can build up a plpgsql statement like this:

   execute 'bpa := ' || function_name || '($1)' using NEW into bpa;

Ideas welcome.

--kt
 

-kt


On Wed, Mar 28, 2012 at 12:54 PM, Kenneth Tilton <ktilton@xxxxxxxx> wrote:
On version:

    PostgreSQL 9.1.2 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.5 20110214 (Red Hat 4.4.5-6), 64-bit

I get this error (all code at end of post) in pgAdmin:

NOTICE:  bpa inbound (,now_plus_30)
CONTEXT:  SQL statement "select now_plus_30(NEW)"
PL/pgSQL function "bp_alert_init" line 7 at SQL statement
NOTICE:  warn time in input row = ("2012-04-27 16:41:20.338239+00",now_plus_30)
CONTEXT:  SQL statement "select now_plus_30(NEW)"
PL/pgSQL function "bp_alert_init" line 7 at SQL statement


ERROR:  invalid input syntax for type timestamp with time zone: "("2012-04-27 16:41:20.338239+00",now_plus_30)"
CONTEXT:  PL/pgSQL function "bp_alert_init" line 7 at SQL statement

********** Error **********

ERROR: invalid input syntax for type timestamp with time zone: "("2012-04-27 16:41:20.338239+00",now_plus_30)"
SQL state: 22007
Context: PL/pgSQL function "bp_alert_init" line 7 at SQL statement


Note that I have eliminated the complexity of the callback and simply call the desired initializer directly. FWIW, using the desired EXECUTE statement produces exactly the same error. 

If I declare the receiving variable to be a record, pgAdmin shows me this:

NOTICE:  bpa inbound (,now_plus_30)
CONTEXT:  SQL statement "select now_plus_30(NEW)"
PL/pgSQL function "bp_alert_init" line 7 at SQL statement
NOTICE:  warn time in input row = ("2012-04-27 16:46:22.62478+00",now_plus_30)
CONTEXT:  SQL statement "select now_plus_30(NEW)"
PL/pgSQL function "bp_alert_init" line 7 at SQL statement
NOTICE:  caller got bpa ("(""2012-04-27 16:46:22.62478+00"",now_plus_30)") <----------------- 


ERROR:  record "bpa" has no field "warn_time"
CONTEXT:  SQL statement "SELECT bpa.warn_time"
PL/pgSQL function "bp_alert_init" line 9 at RAISE

So it looks as if I have to "unwrap" or eval the return value (or change the way I am returning it). But the callee is declared as returning a bp_alert and returns a variable of type bp_alert, so I am not sure what more I can do in the callee. The caller is selecting into a variable of type bp_alert, so that too seems clear.

Hints welcome, code next.

ken

-- code starts here -------------------------------------------------------

set search_path to public;
drop table if exists bp_alert cascade;

CREATE TABLE bp_alert (
  warn_time          timestamp WITH TIME ZONE,
  warn_time_init     text
)

CREATE OR REPLACE FUNCTION now_plus_30(bpa bp_alert)
  RETURNS bp_alert AS
$BODY$
  
declare
begin
   raise notice 'bpa inbound %', bpa;
   bpa.warn_time = now() + interval '30 days';
   raise notice 'warn time in input row = %', bpa;
   return bpa;
end;
$BODY$
  LANGUAGE plpgsql VOLATILE;

CREATE OR REPLACE FUNCTION bp_alert_init()
  RETURNS trigger AS
$BODY$
  
declare
   bpa bp_alert; -- make this a record and the "warn time in caller" raise fails on bpa not having warn_time
begin
   -- no difference: execute 'select ' || NEW.warn_time_init || '($1)' using NEW into bpa;
   select now_plus_30(NEW) into bpa;
   raise notice 'caller got bpa %', bpa;
   raise notice 'warn time in caller now %', bpa.warn_time;
   return bpa;
end;
$BODY$
  LANGUAGE plpgsql VOLATILE;

drop trigger if exists bp_alert on bp_alert;

CREATE TRIGGER bp_alert
  BEFORE INSERT
  ON bp_alert
  FOR EACH ROW
  EXECUTE PROCEDURE bp_alert_init();

insert into bp_alert (warn_time_init) values ('now_plus_30');




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