Writing Clean and Reusable Code in Django

Two views on the blog both show published articles. One writes the filter out in full, and the other calls a single method:

# Written out in each view
Article.objects.filter(is_draft=False, published_date__lte=timezone.now())

# Written once, called everywhere
Article.objects.published()

Both return the same rows today. The difference appears on the day the rule changes, for example when the blog adds a "hidden" flag. The first version must be found and edited in every view that copied it, and one missed copy shows hidden articles. The second version changes in one place.