django-closuretree 1.2.0

django-closuretree is an implementation of the closure tree technique for Django applications designed to provide efficient querying of tree-based structures in a relational database. Its goal is to reduce the number of queries required when querying the children or parents of a given object.

Given the following model:

class Node(models.Model):
    name = models.CharField(max_length=24)
    parent = models.ForeignKey('self', related_name='children')

The children of each model can be queried with:

Node.objects.get(name='A').children.all()

However, for recursive lookups, this results in a large number of queries. Instead, django-closuretree allows you to extract them all in one go:

from closuretree.models import ClosureModel

class Node(ClosureModel):
    name = models.CharField(max_length=24)
    parent = models.ForeignKey('self', related_name='children', null=True)

a = Node.objects.create(name='A')
Node.objects.create(name='B', parent=a)

Node.objects.get(name='A').get_descendants()

A single query will obtain all the descendants.

Node.rebuildtable()