node-red-contrib-postgres-listen

A Node-RED node to listen to pg_notify

Install
-------

Run the following command in the root directory of your Node-RED install

npm install node-red-contrib-postgres-listen

Overview
-------

This add-on, allows to listen to PostgreSQL pg_notify mechanism.

The node takes two parameters :

- postgresdb : The PostgreSQL connection configuration
- channel : The channel name specified in the pg_notify command

PostgreSQL sample code
----------------------

1. Create a base table:

CREATE TABLE realtime
(
id INTEGER DEFAULT nextval('realtime_id_seq'::regclass) NOT NULL,
title CHARACTER VARYING(128),
PRIMARY KEY (id)
);

2. Create a trigger on the table:

CREATE TRIGGER "updated_realtime_trigger"
BEFORE INSERT OR DELETE OR UPDATE ON realtime
FOR EACH ROW
EXECUTE PROCEDURE notify_realtime()

3. Create a trigger function:

CREATE FUNCTION public.notify_realtime()
RETURNS trigger
LANGUAGE 'plpgsql'
COST 100.0
VOLATILE NOT LEAKPROOF
AS $BODY$

BEGIN
PERFORM pg_notify('addedrecord', '' || row_to_json(NEW));
RETURN NEW;
END;
$BODY$;

Result
------

The node will produce a message like that :

{"name":"notification","length":47,"processId":16147,"channel":"addedrecord","payload":{"id":2,"title":"plopcsd"}}

All fields are generated by Postgres with payload being the content of the table row.

Changelog
---------

- 0.2.0 : Removed the postgres configuration Node and created a dependency to https://flows.nodered.org/node/node-red-contrib-postgres making it possible to have both nodes installed.

node-red-contrib-postgres-listen