from datetime import date
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey
from django.db import models
from django.utils.functional import SimpleLazyObject, empty
class Period(object):
DAY = 86400 # seconds
WEEK = DAY * 7
DAYS_28 = DAY * 28
MONTH = DAY * 30
LIFETIME = 0
PERIOD_CHOICES = (
(Period.DAY, 'Day'),
(Period.WEEK, 'Week'),
(Period.DAYS_28, '28 days'),
(Period.MONTH, 'Month'),
(Period.LIFETIME, 'Lifetime'))
class RegisterLazilyManagerMixin(object):
_lazy_entries = []
def _register(self, defaults=None, **kwargs):
"""Fetch (update or create) an instance, lazily.
We're doing this lazily, so that it becomes possible to define
custom enums in your code, even before the Django ORM is fully
initialized.
Domain.objects.SHOPPING = Domain.objects.register(
ref='shopping',
name='Webshop')
Domain.objects.USERS = Domain.objects.register(
ref='users',
name='User Accounts')
"""
f = lambda: self.update_or_create(defaults=defaults, **kwargs)[0]
ret = SimpleLazyObject(f)
self._lazy_entries.append(ret)
return ret
def clear_cache(self):
"""For testability"""
for entry in self._lazy_entries:
entry._wrapped = empty
class DomainManager(RegisterLazilyManagerMixin, models.Manager):
def register(self, ref, name=''):
return super(DomainManager, self)._register(
defaults={'name': name},
ref=ref)
def get_by_natural_key(self, ref):
return self.get(ref=ref)
class Domain(models.Model):
objects = DomainManager()
ref = models.CharField(
max_length=100,
unique=True,
help_text="Unique reference ID for this domain")
name = models.CharField(
max_length=100,
blank=True,
help_text="Short descriptive name")
def __str__(self):
return self.name or self.ref
def natural_key(self):
return [self.ref]
class MetricManager(RegisterLazilyManagerMixin, models.Manager):
def register(self, domain, ref, name='', description=''):
return super(MetricManager, self)._register(
defaults={'name': name,
'description': description},
domain=domain,
ref=ref)
def get_by_natural_key(self, domain, ref):
return self.get(source=domain,
ref=ref)
class Metric(models.Model):
objects = MetricManager()
domain = models.ForeignKey(Domain, on_delete=models.PROTECT)
ref = models.CharField(
max_length=100,
help_text="Unique reference ID for this metric within the domain")
name = models.CharField(
max_length=100,
blank=True,
help_text="Short descriptive name")
description = models.TextField(
blank=True,
help_text="Description")
class Meta:
unique_together = ('domain', 'ref')
def __str__(self):
return self.name or self.ref
def natural_key(self):
return [self.source, self.ref]
class AbstractStatisticQuerySet(models.QuerySet):
order_field = None
def narrow(self, metric=None, metrics=None, period=None):
qs = self
assert metric is None or metrics is None
if metric is not None:
metrics = [metric]
if metrics is not None:
qs = qs.filter(metric__in=metrics)
if period:
qs = qs.filter(period=period)
return qs
def record(self, metric, value, period, **kwargs):
instance, _ = self.update_or_create(
period=period,
metric=metric,
defaults={'value': value},
**kwargs)
return instance
def most_recent(self, **kwargs):
return self.narrow(**kwargs).order_by('-' + self.order_field).first()
class AbstractStatistic(models.Model):
metric = models.ForeignKey(Metric, on_delete=models.PROTECT)
value = models.BigIntegerField(
# To support storing that no data is available, use: NULL
null=True)
period = models.IntegerField(choices=PERIOD_CHOICES)
class Meta:
abstract = True
class ByObjectMixin(models.Model):
object_type = models.ForeignKey(ContentType, on_delete=models.PROTECT)
object_id = models.PositiveIntegerField()
object = GenericForeignKey(
'object_type',
'object_id')
class Meta:
abstract = True
class ByObjectQuerySetMixin(object):
def record(self, **kwargs):
object = kwargs.pop('object')
ct = ContentType.objects.get_for_model(object)
return super(ByObjectQuerySetMixin, self).record(
object_id=object.pk,
object_type=ct,
**kwargs)
def narrow(self, **kwargs):
qs = self
object = kwargs.pop('object', None)
objects = kwargs.pop('objects', None)
object_type = kwargs.pop('object_type', None)
assert object is None or objects is None
if object is not None:
objects = [object]
if object_type:
qs = qs.filter(object_type=object_type)
if type(objects) in (list, tuple, set):
if not objects:
qs = self.none()
else:
# Assumption: all objects are of same type
ct = ContentType.objects.get_for_model(objects[0])
qs = qs.filter(
object_type=ct,
object_id__in=[s.pk for s in objects])
elif isinstance(objects, models.QuerySet):
ct = ContentType.objects.get_for_model(objects.model)
qs = qs.filter(
object_type=ct,
object_id__in=objects.values_list(
'id', flat=True))
elif objects is None:
pass
elif isinstance(objects, models.query.EmptyQuerySet):
qs = self.none()
else:
raise NotImplementedError
return super(ByObjectQuerySetMixin, qs).narrow(**kwargs)
class ByDateMixin(models.Model):
date = models.DateField(db_index=True)
class Meta:
abstract = True
class ByDateQuerySetMixin(object):
order_field = 'date'
def record(self, **kwargs):
dt = kwargs.pop('date', date.today())
return super(ByDateQuerySetMixin, self).record(date=dt, **kwargs)
def narrow(self, **kwargs):
"""Up-to including"""
from_date = kwargs.pop('from_date', None)
to_date = kwargs.pop('to_date', None)
date = kwargs.pop('date', None)
qs = self
if from_date:
qs = qs.filter(date__gte=from_date)
if to_date:
qs = qs.filter(date__lte=to_date)
if date:
qs = qs.filter(date=date)
return super(ByDateQuerySetMixin, qs).narrow(**kwargs)
class StatisticByDateQuerySet(
ByDateQuerySetMixin,
AbstractStatisticQuerySet):
pass
class StatisticByDateAndObjectQuerySet(
ByDateQuerySetMixin,
ByObjectQuerySetMixin,
AbstractStatisticQuerySet):
pass
class StatisticByDate(ByDateMixin, AbstractStatistic):
objects = StatisticByDateQuerySet.as_manager()
class Meta:
unique_together = [
'date',
'metric',
'period']
verbose_name = 'Statistic by date'
verbose_name_plural = 'Statistics by date'
def __str__(self):
return '{date}: {value}'.format(
date=self.date,
value=self.value)
class StatisticByDateAndObject(
ByDateMixin,
ByObjectMixin,
AbstractStatistic):
objects = StatisticByDateAndObjectQuerySet.as_manager()
class Meta:
unique_together = [
'date',
'metric',
'object_type',
'object_id',
'period']
verbose_name = 'Statistic by date and object'
verbose_name_plural = 'Statistics by date and object'
def __str__(self):
return '{date}: {value}'.format(
date=self.date,
value=self.value)
