django-denormalized 0.1.1

Utils for maintaining denormalized aggregates for Django models

django-denormalized

Utils for maintaining denormalized aggregates for Django models.

Example

from django.db import models
from denormalized import DenormalizedTracker, DenormalizedForeignKey


class Group(models.Model):
    members_count = models.PositiveIntegerField(default=0)
    points_sum = models.PositiveIntegerField(default=0)


class Member(models.Model):
    group = DenormalizedForeignKey(
        Group, models.CASCADE,
        trackers=[DenormalizedTracker(
            # name of field to store denormalized count of active members
            "members_count",                    
            # callback to determine whether object should be counted or not
            callback=lambda obj: obj.active,
            # QuerySet filter to count only suitable objects
            query=models.Q(active=True)),
            DenormalizedTracker(
            # multiple denormalized fields may be tracked for single foreign key
            "points_sum",
            # Sum is also supported
            aggregate=models.Sum("points"))
        ])
    active = models.BooleanField(default=True)
    points = models.IntegerField(default=0)