Get individual columns from function returning SETOF <composite type>

Question

I created function like below:

CREATE TYPE points AS (
    "gid" double precision
  , "elevation" double precision
  , "distance" double precision
  , "x" double precision
  , "y" double precision
);    

CREATE OR REPLACE FUNCTION public.nd_test4()
RETURNS  SETOF points AS $$

DECLARE     
    sql text;
    rec points;             
BEGIN       
    sql := 'select
        "gid"
        , "elev" as "elevation"
        , st_distance(ST_MakePoint(1093147, 1905632) , "the_geom" ) as "distance"
        , st_x("the_geom") as "x"
        , st_y("the_geom")as "y"
    from
        "elevation-test"
    where
        st_within("the_geom" ,st_buffer(ST_MakePoint(1093147, 1905632), 15) )
    order by distance limit 4';

    FOR rec IN EXECUTE(sql) LOOP
        RETURN NEXT rec;

    END LOOP;                                   
END;
    $$ LANGUAGE plpgsql VOLATILE;

And when I run the function like select nd_test4();, I get a result with no filed names like below.

image?

How can I get result with filed name like this:

gid | elevation | distance | x       | y
----+-----------+----------+---------+-------
 1  | 350.0     | 10       | 12345.1 | 12435 

Answer 1

Call the function with:

SELECT * FROM nd_test4();

Also, your function definition is needlessly convoluted. Simplify to:

CREATE OR REPLACE FUNCTION public.nd_test4()
  RETURNS SETOF points AS
$func$
BEGIN

RETURN QUERY
SELECT gid
      ,elev           -- AS elevation
      ,st_distance(ST_MakePoint(1093147, 1905632) , the_geom ) -- AS distance
      ,st_x(the_geom) -- AS x
      ,st_y(the_geom) -- AS y
FROM   "elevation-test"
WHERE  st_within(the_geom, st_buffer(ST_MakePoint(1093147, 1905632), 15))
ORDER  BY distance
LIMIT  4;

END
$func$ LANGUAGE plpgsql;

Or better yet, use a plain SQL function here:

CREATE OR REPLACE FUNCTION public.nd_test4()
  RETURNS SETOF points AS
$func$
SELECT gid
      ,elev           -- AS elevation
      ,st_distance(ST_MakePoint(1093147, 1905632) , the_geom ) -- AS distance
      ,st_x(the_geom) -- AS x
      ,st_y(the_geom) -- AS y
FROM  "elevation-test"
WHERE  st_within(the_geom, st_buffer(ST_MakePoint(1093147, 1905632), 15))
ORDER  BY distance
LIMIT  4
$func$ LANGUAGE sql;

• No need for dynamic SQL.

• I also stripped the gratuitous double quotes. Not needed for legal, lower-case identifiers. Exception is "elevation-test". You shouldn't use an operator (-) as part of a table name. That's just begging for trouble.

• Aliases in the function body are replaced by column names of the composite type. They are only visible inside the function and therefore just documentation in your case.