How to Order Django Query Results with NULLS LAST in PostgreSQL?

Ordering Query Results with "NULLS LAST" in Django

When working with PostgreSQL, you may encounter a scenario where you desire to sort model results prioritizing non-null values over nulls using the "NULLS LAST" option.

Attempt and Issue

An initial approach using extra(order_by=('-price', 'NULLS LAST')) may result in the error, "Cannot resolve keyword 'NULLS LAST' into field."

Solution

To achieve the desired sorting behavior, utilize the following solution introduced in Django 1.11:

from django.db.models import F
MyModel.objects.all().order_by(F('price').desc(nulls_last=True))

This syntax utilizes the F expression provided by Django, allowing you to specify field sorting with customizable parameters. The desc(nulls_last=True) argument ensures that null values are treated as the last elements in the sorted results.

Reference

For further information, refer to the official Django documentation for versions 1.11 and 3.1:

• Django 1.11: https://docs.djangoproject.com/en/dev/releases/1.11/#expression-asc-and-desc-nulls-first-and-nulls-last-parameters
• Django 3.1: https://docs.djangoproject.com/en/3.1/ref/models/expressions/#using-f-to-sort-null-values

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