https://github.com/shawalli/psycopg2-pgevents

PostGreSQL LISTEN/NOTIFY functionality, via psycopg2.
https://github.com/shawalli/psycopg2-pgevents

Last synced: 5 days ago
JSON representation

PostGreSQL LISTEN/NOTIFY functionality, via psycopg2.

• Host: GitHub
• URL: https://github.com/shawalli/psycopg2-pgevents
• Owner: shawalli
• License: mit
• Created: 2018-08-20T01:45:49.000Z (about 6 years ago)
• Default Branch: master
• Last Pushed: 2021-08-10T16:55:37.000Z (about 3 years ago)
• Last Synced: 2024-10-26T00:10:22.002Z (13 days ago)
• Language: Python
• Size: 58.6 KB
• Stars: 12
• Watchers: 1
• Forks: 4
• Open Issues: 4
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE.txt

Awesome Lists containing this project

README

        
#################

psycopg2-pgevents

#################

.. image:: https://badge.fury.io/py/psycopg2-pgevents.svg

    :target: https://badge.fury.io/py/psycopg2-pgevents

.. image:: https://coveralls.io/repos/github/shawalli/psycopg2-pgevents/badge.svg?branch=master

    :target: https://coveralls.io/github/shawalli/psycopg2-pgevents?branch=master

.. image:: https://img.shields.io/badge/License-MIT-yellow.svg

    :target: https://opensource.org/licenses/MIT

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``.

.. code-block:: python

    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.