Vfrdtyky

My application connects to a database and listens for events, so it can execute the events. If the connection with the database drops, then it's supposed to be able to detect it with consumer.db.on('error'

Relevant documentation:

client.on('error', (err: Error) => void) => void

When the client is in the process of connecting, dispatching a query, or disconnecting it will catch and foward errors from the PostgreSQL server to the respective client.connect client.query or client.end callback/promise; however, the client maintains a long-lived connection to the PostgreSQL back-end and due to network partitions, back-end crashes, fail-overs, etc the client can (and over a long enough time period will) eventually be disconnected while it is idle. To handle this you may want to attach an error listener to a client to catch errors. Here's a contrived example:

const client = new pg.Client()

client.connect()



client.on('error', (err) => {

  console.error('something bad has happened!', err.stack)

})



// walk over to server, unplug network cable



// process output: 'something bad has happened!' followed by stacktrace :P

Here is my code, trying to do the same thing:

var pg = require('pg');



// get the connection from the connection pool

pg.connect('pg://some:user@some.server', function(err, db){



  // throw error

  if(err) {

    // handle the error - reconnect and log

  }



  // set database connection for global use

  consumer.db = db;



  // when notification received

  consumer.db.on('notification', function(event){

    console.log(event);

    // do something with the event

  });



  // Detect network disruption and other errors

  consumer.db.on('error', function(event){

    console.log("Error!")

    // handle the error - reconnect and log

  });

});

I tested this functionality by turning off the wifi for 5 minutes. Sure enough, the connection dropped, but no error event was created, and nothing got logged to the console. I also tried shutting down the remote database with the same results.

How can I get an error when the connection drops?

The problem was an old version of pg

The default pool and pg.connect(...) were removed in v7.0.0: https://github.com/brianc/node-postgres/blob/master/CHANGELOG.md#700

Also, it looks like client.on('error', ...) didn't support network disruptions at that time.

Upgrading to ^7.0.0

My version of pg was 4.5.7.

After upgrading to the latest version of pg (7.6.1) and replacing

pg.connect('pg://some:user@some.server', function(err, db){

with

const connectionConfig = {

    host: config.database.server,

    port: config.database.port,

    database: config.database.database,

    user: config.database.username,

    password: config.database.password

  }

  // get the connection from the connection pool

  consumer.pool = new pg.Pool(connectionConfig)

  consumer.pool.on('error', function(error) {

    consumer.handleError();

    return;

  });

  consumer.pool.connect(function(err, db){

The issue was fixed.