Skip to main content

PostGreSQL LISTEN/NOTIFY functionality, via psycopg2.

Project description

https://circleci.com/gh/shawalli/psycopg2-pgevents.svg?style=svg https://coveralls.io/repos/github/shawalli/psycopg2-pgevents/badge.svg?branch=master https://img.shields.io/badge/License-MIT-yellow.svg

This package makes it simple to use PostGreSQL’s NOTIFY/LISTEN eventing system from Python in a consistent, pleasing manner.

Note that this project officially supports Python 3.6+. This is primarily due to static typing.

Example

The following shows an example of the package in action.

Assumptions

  • PostGreSQL server is running locally.
  • default database (postgres) is available.
  • table exists in database in the public schema with the name orders.
from psycopg2 import connect
from psycopg2_pgevents.trigger import install_trigger, \
    install_trigger_function, uninstall_trigger, uninstall_trigger_function
from psycopg2_pgevents.event import poll, register_event_channel, \
    unregister_event_channel

connection = connect(dsn='postgres:///postgres')
connection.autocommit = True

install_trigger_function(connection)
install_trigger(connection, 'orders')
register_event_channel(connection)

try:
    print('Listening for events...')
    while True:
        for evt in poll(connection):
            print('New Event: {}'.format(evt))
except KeyboardInterrupt:
    print('User exit via Ctrl-C; Shutting down...')
    unregister_event_channel(connection)
    uninstall_trigger(connection, 'orders')
    uninstall_trigger_function(connection)
    print('Shutdown complete.')

Troubleshooting

  • The connection’s autocommit property must be enabled for this package to operate correctly. This requirement is provided by PostGreSQL’s NOTIFY/LISTEN mechanism.
  • The same connection that is used with register_event_channel() must be used with poll() in order to receive events. This is due to the nature of how PostGreSQL manages “listening” connections.
  • If the table that you’d like to listen to is not in the public schema, the schema name must be given as a keyword argument in the install_trigger() method.

Authorship and License

Written by Shawn Wallis and distributed under the MIT license.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
psycopg2_pgevents-0.1.1-py3-none-any.whl (9.7 kB) Copy SHA256 hash SHA256 Wheel py3
psycopg2-pgevents-0.1.1.tar.gz (9.2 kB) Copy SHA256 hash SHA256 Source None

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page