bitfield_manager¶
Automatic bitfield management for Django Models.
Quickstart¶
Install bitfield_manager:
pip install django-bitfield-manager
Add it to your INSTALLED_APPS:
INSTALLED_APPS = (
...
'bitfield_manager',
...
)
Usage¶
First you’ll need a parent model with a status field
from django.db import models
from bitfield_manager.models import ParentBitfieldModel, ChildBitfieldModelMixin
class ParentExample(ParentBitfieldModel):
status = models.BigIntegerField()
def __str__(self): # __unicode__ on Python 2
return "status: %i" % self.status
Then for all models you want django-bitfield-manager to manage add the BitfieldMeta with a list of parent models. The list of parent models takes in a tuple. The first field is the source that will be modified. The source should be a BigIntegerField or BitField (if using django-bitfield). The 2nd field is the bitflag to use (i.e. 0 will be 1 << 0, 1 will be 1 << 1, etc.)
class ChildExample1(ChildBitfieldModelMixin, models.Model):
parent = models.ForeignKey('ParentExample', null=True)
class BitfieldMeta:
parent_models = [('parent', 'status', 0)]
class ChildExample2(ChildBitfieldModelMixin, models.Model):
parent = models.ForeignKey('ParentExample', null=True)
class BitfieldMeta:
parent_models = [('parent.status', 1)]
Now when creating/deleting child models the parent status should update
# create the model
p = ParentExample.objects.create(status=0)
p2 = ParentExample.objects.create(status=0)
# add a child p.status is now 1
c1 = ChildExample1.objects.create(parent=p)
# add the other child. p.status is now 3
c2 = ChildExample2.objects.create(parent=p)
# deleting a child will refresh the status. p.status is now 2
c1.delete()
# updates or mass deletes will require manual refresh
# p.status will be 2 and p2.status will be 0
ChildExample2.objects.filter(parent=p).update(parent=p2)
# trigger a manual refresh. p.status is now correct with a status of 0
p.force_status_refresh()
# if you know the related models modified you can specify them
# p2.status is now 2
p2.force_status_refresh(related_models=[ChildExample2])
# force status refresh will work with models multiple levels deep. Specify the search_depth to search
# more than 1 level deep
p2.force_status_refresh(search_depth=2)
Django Bitfield Example¶
from django.db import models
from bitfield_manager.models import ParentBitfieldModelMixin, ChildBitfieldModelMixin
from bitfield import BitField
class Person(ParentBitfieldModelMixin, models.Model):
name = models.CharField(max_length=255)
status = BitField(flags=(
('has_children', 'Has Children'),
('has_a_home', 'Has a Home'),
('has_a_car', 'Has a car')
))
def __str__(self):
return "NAME: %s STATUS: %s" % (self.name, ",".join([str(s) for s in self.status]))
class Car(ChildBitfieldModelMixin, models.Model):
make = models.CharField(max_length=255)
model = models.CharField(max_length=255)
owner = models.ForeignKey('Person')
class BitfieldMeta:
parent_models = [('owner.status', Person.status.has_a_car)]
class Child(ChildBitfieldModelMixin, models.Model):
name = models.CharField(max_length=255)
parent = models.ForeignKey('Person')
class BitfieldMeta:
parent_models = [('parent.status', Person.status.has_children)]
class Home(ChildBitfieldModelMixin, models.Model):
owner = models.ForeignKey('Person')
class BitfieldMeta:
parent_models = [('owner.status', Person.status.has_a_home)]
Features¶
- Allows for automatic bitfield management for Django Models.
- Will update the status when models are added or deleted
- Supports multi-level relationships (use dot syntax)
- Supports django-bitfield
Running Tests¶
Does the code actually work?
source <YOURVIRTUALENV>/bin/activate
(myenv) $ pip install tox
(myenv) $ tox