postgres (8.3), useing query result in function

Question

I am trying to create a function to populate 2 tables, the second query containing the new id from the first insert.

an example of some of my tables:

CREATE TABLE message
(
  message_id bigserial NOT NULL,
  member_id bigint NOT NULL,
  message character varying(8192) NOT NULL,
  ...
)

CREATE TABLE feed_message
(
  feed_id bigint NOT NULL,
  message_id bigint NOT NULL
)

what i am trying to do is insert a new message in the message table, and use the generated message_id to populate the feed_message table

i tried writing a function using the pltcl language but i cant figure out how to use the SPI_getvalue to get the just created tupil

this is what i have so far:

/* message_post(entity, id, member_id, title, message, reactionTo) */
CREATE OR REPLACE FUNCTION message_post ()
 RETURNS VOID
 LANGUAGE pltcl
AS $BODY$
 ret_status = spi_exec -count 1 "INSERT INTO message (member_id, title, message) VALUES ($3, $4, $5)"
 IF (ret_status == SPI_OK_SELECT && SPI_processed > 0) {
  //get the tupil from *SPI_tuptable
  set message_id <the new message_id>
 }
 spi_exec -count 1 "INSERT INTO $1_message ($1_id, message_id) VALUES ($2,$message_id)"
$BODY$;

/* useage */
SELECT message_post('feed',12,1,'title','message');

Answer 1

You've got a few places where your Tcl usage (PL/Tcl can be considered to be a dialect, with wrapping) is just plain wrong. I'd guess that this is correct, based on the examples in the PL/Tcl documentation.

CREATE OR REPLACE FUNCTION message_post(text,integer,integer,text,text)
RETURNS VOID AS $$
   set ret_status [spi_exec -count 1 \
         "INSERT INTO message (member_id, title, message) \
               VALUES ($3, '[quote $4]', '[quote $5]')"]
   if {$ret_status > 0} {
      set message_id [spi_lastoid]
      spi_exec -count 1 "INSERT INTO ${1}_message (${1}_id, message_id) \
                         VALUES ($2, $message_id)"
   }
$$ LANGUAGE pltcl;

However, I would not consider this to be idiomatic! After all, it's doing quote and other things like that. As I understand it, this is better:

CREATE OR REPLACE FUNCTION message_post(text,integer,integer,text,text)
RETURNS VOID AS $$
   # Precompile the INSERTs if they didn't already exist
   if {![info exists GD(post_message_plan)]} {
      set GD(post_message_plan) [spi_prepare \
            {INSERT INTO message (member_id, title, message) VALUES ($1, $2, $3)} \
            {integer text text}]
   }
   if {![info exists GD(assoc_message_plan:$1)]} {
      set GD(assoc_message_plan:$1) [spi_prepare \
            "INSERT INTO ${1}_message (${1}_id, message_id) VALUES (\$1, \$2)" \
            {integer integer}]
   }
   # Run the pair of INSERTs
   if {[spi_execp -count 1 $GD(post_message_plan) [list $3 $4 $5]] > 0} {
      spi_execp -count 1 $GD(assoc_message_plan:$1) [list $2 [spi_lastoid]]
   }
$$ LANGUAGE pltcl;

Other things to note: I believe it is spi_lastoid that you're looking for for finding the message id, and I've not actually checked whether your SQL is correct. Also, I may have the types of the arguments to various things wrong. (PostgreSQL and Tcl have quite different ideas about what types are.)