Feature Request: LISTEN support (ie. NotificationResponse)

[andrepl]

the _MSG_NOTIFICATION_RESPONSE is defined in the code, but the message type is not implemented.

There are a few ways to implement this, but simply providing a conn.listen("channel") that returns a stream seems the most obvious and idiomatic to me. the postgres listen command operates 'per-connection' and doesn't block, so I'm not sure how this would interact with pools (if at all).

[xxgreg]

Thanks for the feedback. I'm happy to take patches - but I am not planning on adding this at the moment.

Good point about the connection pools and listen. I guess you'd always want to have a separate connection (not from a pool) open to handle listen responses.

[adaojunior]

Thank you for the package, it's very helpfull,
and I'll also add a +1 for this feature, I was going to use it to create a pubsub in my app but unfortunately there's no LISTEN support.
I take a look in the source code but I'm not sure if I'm able to implement this by myself.

[aabluedragon]

Yet another +1 for this feature request.

[aabluedragon]

I've forked and added support for retrieving Notifications.
See https://github.com/aabluedragon/dart_postgresql.git
Works in a similar fashion to the Java PostgreSQL getNotification() method (where polling seems to be the way to do this in the Java Driver as well).

[Fox32]

Wouldn't a Stream based API be more suiteable for Dart?

[aabluedragon]

It would, but I haven't found a way to have the PostgreSQL connection just give you the received pending notifications without "asking" for it.
Java also has Streams, yet the official PostgreSQL driver also works that way over there.
You can wrap the call to getNotification() with an interval timer, and have it load the upcoming notifications to a Stream using Dart's StreamController.