PostgreSQL Notification Listener

This project is a Python library that listens to notifications from a PostgreSQL database. It provides a simple way to execute functions when specific events happen in the database.

How it works

The listener connects to the PostgreSQL database and sets up a notification channel. You can then attach callbacks to this channel, which will be executed whenever a notification is received.

Installation

To install the library, run: pip install postgresql-notification-listener

Usage

To use this library, follow these steps:

• Import the library in your Python script: from postgresql_notification_listener import NotificationListener
• Create instance of the listener listener = NotificationListener("host=your_host port=your_port dbname=your_database user=your_username password=your_password")
• Define a callback function that will be executed when a notification is received.
• Use the subscribe_to_channel method to attach your callback function to the notification channel: listener.subscribe_to_channel("channel_to_listen", callback_function)
• Start listening for notifications by calling the start method: listener.start()
• You can trigger a notification from PostgreSQL by NOTIFY channel_to_listen statement.
• The start method will call all attached callbacks once when called. If you don't want this behaviour, pass the initial_run=False argument to the start method: listener.start(initial_run=False)
• You can get the notification that caused the callback from the last_notification attribute on the listener instance listener.last_notification

API

• NotificationListener: The main class of this library. It is responsible for setting up a notification channel and managing callbacks.
  • subscribe_to_channel : Attaches a callback function to a specific channel. The subscribe_to_channel method takes two required parameters: the name of the channel to listen to and the callback function to execute when a notification is received.
  • start : Starts listening for notifications. If you don't want all attached callbacks to be called once when called, pass initial_run=False as an argument.
  • last_notification: Returns the latest notification that caused a callback.