[HACKERS] REPOST from SQL List: Use of Setof Record Dynamically

[A E]

Hi,

I am attempting to use Setof Record dynamically. I am developing an application where I will not know what the end-user is trying to work with from a web front end. Thus I will not know before hand the structure of the table I am trying to pull the record from.

My Code:

CREATE FUNCTION retrievecollection(varchar, varchar, varchar) RETURNS record AS'Declaretablealias ALIAS FOR $1;crmid ALIAS FOR $2;username ALIAs FOR $3;allowed integer;objectdefinition record;realtablename char;
beginselect into allowed secverf(username, tablealias);if allowed = 0 thenRAISE NOTICE ''User not authorized to perform retrieve.'', allowed;RETURN false;elseselect into realtablename tablename from applicationaliases where tablealias = qoute_literal(tablealias);if length(crmid) = 0 thenFOR objectdefinition IN SELECT * from qoute_ident(realtablename) LOOPRETURN NEXT objectdefinition;END LOOP;elseFOR objectdefinition IN SELECT * from qoute_ident(realtablename) where crmid = qoute_literal(crmid) LOOPRETURN NEXT objectdefinition;END LOOP;end if;end if;RETURN record;end;'LANGUAGE 'plpgsql' VOLATILE;
I know that I would execute the procedure with select * from retrievecollection as x(x typex, y typey) but how do I do this if I don't know which table was passed to the function?
TIA
Alex Erwin

Re: [HACKERS] REPOST from SQL List: Use of Setof Record Dynamically

[Joe Conway]

A E wrote:
I am attempting to use Setof Record dynamically. I am developing an
application where I will not know what the end-user is trying to work
with from a web front end. Thus I will not know before hand the
structure of the table I am trying to pull the record from.
[code]

I know that I would execute the procedure with select * from
retrievecollection as x(x typex, y typey) but how do I do this if I
don't know which table was passed to the function?
The short answer is there is no way to do what you seem to want to do,
at least not directly.
You might try storing a suitable column definition string (columndef) 
in the applicationaliases table for each referenced table. From your 
web page first do:

  SELECT columndef
  FROM applicationaliases
  WHERE tablealias = qoute_literal(tablealias);
Alternatively you could dynamically build the columndef based on tablename.

Then use the result to build the second query; something like:

  SELECT *
  FROM retrievecollection($tablealias, $crmid, $username)
  AS ($columndef);
HTH,

Joe

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