Annotate age for user from birthday

script.py

from django.db.models import (
    Avg,
    Count,
    DateField,
    ExpressionWrapper,
    F,
    IntegerField,
    Min,
    Q,
    Value
)
from django.db.models.functions import ExtractDay


qs = (
    EventEntryChild.objects
    .annotate(
        years_age=ExpressionWrapper(
            ExtractDay(
                ExpressionWrapper(
                    Min('event_entry__dates__date') - F('child__birthday'),
                    output_field=DateField()
                )
            )
            /
            365.25,
            output_field=IntegerField()
        ),
    )
    .values('years_age')
    .filter(years_age__isnull=False)
    .annotate(
        town=F('event_entry__event__town__title'),
    )
    .annotate(total=Count('years_age'))
    .order_by('town', 'years_age')
)