Trending factor calculation

trending.py

def get_overall_score_trending_factor_queryset(self, queryset):
        duration = Epoch((F('now') - F('created_at')))

        queryset = queryset.annotate(
            now=Cast(timezone.now(), DateTimeField()),
            duration=duration,
            trending_factor=ExpressionWrapper(
                # the 10 ^ 6 * 3600 * 24 * 30 multiplication is to convert micro second duration to months
                (F('score__overall_score') * 1_000_000 * 3600 * 24 * 30) / F('duration'),
                output_field=DecimalField()
            )).order_by(F('trending_factor').desc(nulls_last=True))

        return queryset

how do you import the Epoch field

Oh yes, that's a custom-made query expression.

from django.db.models import Func, IntegerField

class Epoch(Func):
    template = 'EXTRACT(epoch FROM %(expressions)s)::INTEGER'
    output_field = IntegerField()