All imports are from:
from cte_tree.models import ...
If a custom Manager is specified, it must inherit from CTENodeManager:
class CategoryManager(CTENodeManager): ... class Category(CTENode): name = CharField(max_length = 128, null = False) objects = CategoryManager() def __unicode__(self): return '%s @ %s' % (self.name, self.depth)
It is possible to add the fields for ‘depth’, ‘path’, and ‘ordering’ as normal fields to a Django model, so that mechanics of Django, third party, or your own modules find them. Doing so will create columns for them in the database, but their values will always be overridden by the materialized CTE table. They will also never be written (unless you explicitly do so) through an UPDATE query, meaning the columns will remain empty. Although this is wasteful, it may be useful or even necessary, given that Django does not cater for non-managed fields (only entire models).
Therefore, the fields package provides three such fields which are automatically set to null, blank, and non-editable, and can be used as such:
from cte_tree.fields import DepthField, PathField, OrderingField class Category(CTENode): depth = DepthField() path = PathField() ordering = OrderingField() name = CharField(max_length = 128, null = False) objects = CategoryManager() def __unicode__(self): return '%s @ %s' % (self.name, self.depth)