Django Postgres Current Timestamp

Add true postgresql CURRENT_TIMESTAMP support to Django + PostgreSQL.

Also includes automatic support for usage in auto_now and auto_now_add DateTimeField columns in models.

About

Author: Jay Taylor / ThreatStream

License: BSD

Out of the box, (at least as of version 1.7) Django uses python-generated timestamps rather than using CURRENT_TIMESTAMP SQL statements. This plugin module provides the ability to regain this fine-grained control over temporal aspects of the database.

Installation and Usage

1. Install the django_pg_current_timestamp package.

Automatically via pip + pypi:

pip install django-pg-current-timestamp

Automatically via pip + github:

pip install -e git+https://github.com/threatstream/django-pg-current-timestamp.git#egg=django-pg-current-timestamp

Manually:

git clone https://github.com/threatstream/django-pg-current-timestamp.git
cd django-pg-current-timestamp
python setup.py build
python setup.py install

2. Add django_pg_current_timestamp to list of INSTALLED_APPS in settings.py.

settings.py:

INSTALLED_APPS += ['django_pg_current_timestamp']

3. Activate automatic support for DateTimeField auto_now=True and

auto_now_add=True columns by running the package's init() method in settings.py.

settings.py (add to very end, see "caveats" below for details):

import django_pg_current_timestamp
django_pg_current_timestamp.init()

Manual use of and control over CURRENT_TIMESTAMP statements is now achievable

from django_pg_current_timestamp import CurrentTimestamp

mm = MyModel.objects.get(id=1)
mm.last_seen_date = CurrentTimestamp()
mm.save()
## Resulting SQL:
##     UPDATE "my_model" SET "last_seen_date" = CURRENT_TIMESTAMP;

print MyModel.objects.filter(last_seen_date__lt=CURRENT_TIME).count()

MyModel.objects.filter(id__in=[1, 2, 3]).update(last_seen_date=CURRENT_TIME)

Running the test suite

Grab the source code:

git clone https://github.com/threatstream/django_pg_current_timestamp.git
cd django_pg_current_timestamp

Ensure a postgres database named "django_pg_current_timestamp" is available and can be reached from your environment without a password (otherwise it is necessary to edit DATABASES in runtests.py):

psql -c 'CREATE DATABASE "django_pg_current_timestamp";'

Then simply execute the test runner:

python runtests.py

Publishing instructions

rm -rf build dist *.egg-info && ./setup.py clean && ./setup.py build && ./setup.py sdist && twine upload dist/*

Caveat Emptor

Presently there several edge cases to be aware of.

Fake-ish timestamps because we don't know the actual value for db CURRENT_TIMESTAMP

The timestamp returned after saving a DateTimeField model attribute of the auto_now/auto_now_add variety, or a field set to CurrentTimestamp() will not be the real value from the database. It will be a timestamp generated using Django's timezone.now(). To get the real timestamp it is necessary to retrieve the object fresh from the database.

django_pg_current_timestamp.init()

Keep django_pg_current_timestamp initialization at the end of settings.py to avoid side-effects which can cause oddities in django behavior. This is due to the monkey patching we do on django.