Improve error messages

[okjulian]

PostgresPubSub instances emit a special event called "error". This event's payload is an instance of Javascript's Error. You can get the error's text using error.message.

const ps = new PostgresPubSub({ client });
 ps.subscribe("error", err => {
  console.log(err.message); // -> "payload string too long"
}).then(() => ps.publish("a", "a".repeat(9000)));

For example you can log all error messages (including stack traces and friends) using something like this:

ps.subscribe("error", console.error);

[derekpitt]

Looks like it will still send the message, so I'm afraid that it is still going to kill my web server. (although, I will for sure double check)

Maybe the responsibility of the message length check should be on pg-ipc?

I'm also gonna check out some of the other implementations to see if they have to check for limitations.

Thanks for including me in this one! Really don't like the idea of introducing new infra to have cross process communication

[okjulian]

You need to listen for the error message. If you do that, your server won't crash. There's an underlying NodeJS Event Emitter that receives an error event when there is a message with over 8000 characters. As you can read in the official docs, any unhandled error event in a NodeJS event emitter will throw an error and terminate the process.

@derekpitt did you try if this is the case? Adding ps.subscribe("error", console.error); to your web server should prevent it from crashing.

[derekpitt]

Oh man! I never knew that error events were special!

Well then, I love this :)

[okjulian]

Awesome! Thanks so much for your help Derek 😄