Updated page admin/add form to use the same method for redirection as the 1.3 user...
[philo.git] / models / base.py
index bd55e95..af1e880 100644 (file)
-# encoding: utf-8
-from django.utils.translation import ugettext_lazy as _
-from django.contrib.auth.models import User, Group
-from django.contrib.contenttypes import generic
-from django.contrib.contenttypes.models import ContentType
+from django import forms
 from django.db import models
-from django.contrib.sites.models import Site
-from philo.utils import fattr
-from django.template import add_to_builtins as register_templatetags
-from django.template import Template as DjangoTemplate
-from django.template import TemplateDoesNotExist
-from django.template import Context, RequestContext
+from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes import generic
 from django.core.exceptions import ObjectDoesNotExist
+from django.core.validators import RegexValidator
 from django.utils import simplejson as json
+from django.utils.encoding import force_unicode
+from philo.exceptions import AncestorDoesNotExist
+from philo.models.fields import JSONField
+from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter
+from philo.signals import entity_class_prepared
+from philo.validators import json_validator
 from UserDict import DictMixin
-from philo.templatetags.containers import ContainerNode
-from django.template.loader_tags import ExtendsNode, ConstantIncludeNode, IncludeNode
-from django.template.loader import get_template
-from django.http import Http404, HttpResponse, HttpResponseServerError, HttpResponseRedirect
-from django.core.servers.basehttp import FileWrapper
-from django.conf import settings
-from philo.validators import RedirectValidator
-
-
-def register_value_model(model):
-       pass
+from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions
 
 
-def unregister_value_model(model):
-       pass
-
-
-class Attribute(models.Model):
-       entity_content_type = models.ForeignKey(ContentType, verbose_name='Entity type')
-       entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
-       entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
-       key = models.CharField(max_length=255)
-       json_value = models.TextField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.')
-       
-       def get_value(self):
-               return json.loads(self.json_value)
-       
-       def set_value(self, value):
-               self.json_value = json.dumps(value)
-       
-       def delete_value(self):
-               self.json_value = json.dumps(None)
-       
-       value = property(get_value, set_value, delete_value)
+class Tag(models.Model):
+       name = models.CharField(max_length=255)
+       slug = models.SlugField(max_length=255, unique=True)
        
        def __unicode__(self):
-               return u'"%s": %s' % (self.key, self.value)
+               return self.name
        
        class Meta:
                app_label = 'philo'
+               ordering = ('name',)
 
 
-class Relationship(models.Model):
-       entity_content_type = models.ForeignKey(ContentType, related_name='relationship_entity_set', verbose_name='Entity type')
-       entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
-       entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
-       key = models.CharField(max_length=255)
-       value_content_type = models.ForeignKey(ContentType, related_name='relationship_value_set', verbose_name='Value type')
-       value_object_id = models.PositiveIntegerField(verbose_name='Value ID')
-       value = generic.GenericForeignKey('value_content_type', 'value_object_id')
+class Titled(models.Model):
+       title = models.CharField(max_length=255)
+       slug = models.SlugField(max_length=255)
        
        def __unicode__(self):
-               return u'"%s": %s' % (self.key, self.value)
+               return self.title
        
        class Meta:
-               app_label = 'philo'
+               abstract = True
 
 
-class QuerySetMapper(object, DictMixin):
-       def __init__(self, queryset, passthrough=None):
-               self.queryset = queryset
-               self.passthrough = passthrough
-       def __getitem__(self, key):
-               try:
-                       return self.queryset.get(key__exact=key).value
-               except ObjectDoesNotExist:
-                       if self.passthrough:
-                               return self.passthrough.__getitem__(key)
-                       raise KeyError
-       def keys(self):
-               keys = set(self.queryset.values_list('key', flat=True).distinct())
-               if self.passthrough:
-                       keys += set(self.passthrough.keys())
-               return list(keys)
+value_content_type_limiter = ContentTypeRegistryLimiter()
 
 
-class Entity(models.Model):
-       attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
-       relationship_set = generic.GenericRelation(Relationship, content_type_field='entity_content_type', object_id_field='entity_object_id')
-       
-       @property
-       def attributes(self):
-               return QuerySetMapper(self.attribute_set)
-       
-       @property
-       def relationships(self):
-               return QuerySetMapper(self.relationship_set)
-       
-       class Meta:
-               abstract = True
-               app_label = 'philo'
+def register_value_model(model):
+       value_content_type_limiter.register_class(model)
 
 
-class Collection(models.Model):
-       name = models.CharField(max_length=255)
-       description = models.TextField(blank=True, null=True)
-       
-       @fattr(short_description='Members')
-       def get_count(self):
-               return self.members.count()
-       
-       def __unicode__(self):
-               return self.name
-       
-       class Meta:
-               app_label = 'philo'
+register_value_model(Tag)
 
 
-class CollectionMemberManager(models.Manager):
-       use_for_related_fields = True
-
-       def with_model(self, model):
-               return model._default_manager.filter(pk__in=self.filter(member_content_type=ContentType.objects.get_for_model(model)).values_list('member_object_id', flat=True))
+def unregister_value_model(model):
+       value_content_type_limiter.unregister_class(model)
 
 
-class CollectionMember(models.Model):
-       objects = CollectionMemberManager()
-       collection = models.ForeignKey(Collection, related_name='members')
-       index = models.PositiveIntegerField(verbose_name='Index', help_text='This will determine the ordering of the item within the collection. (Optional)', null=True, blank=True)
-       member_content_type = models.ForeignKey(ContentType, verbose_name='Member type')
-       member_object_id = models.PositiveIntegerField(verbose_name='Member ID')
-       member = generic.GenericForeignKey('member_content_type', 'member_object_id')
-       
-       def __unicode__(self):
-               return u'%s - %s' % (self.collection, self.member)
+class AttributeValue(models.Model):
+       attribute_set = generic.GenericRelation('Attribute', content_type_field='value_content_type', object_id_field='value_object_id')
        
-       class Meta:
-               app_label = 'philo'
-
-
-class TreeManager(models.Manager):
-       use_for_related_fields = True
+       def set_value(self, value):
+               raise NotImplementedError
        
-       def roots(self):
-               return self.filter(parent__isnull=True)
+       def value_formfields(self, **kwargs):
+               """Define any formfields that would be used to construct an instance of this value."""
+               raise NotImplementedError
        
-       def get_with_path(self, path, root=None, absolute_result=True, pathsep='/'):
-               """
-               Returns the object with the path, or None if there is no object with that path,
-               unless absolute_result is set to False, in which case it returns a tuple containing
-               the deepest object found along the path, and the remainder of the path after that
-               object as a string (or None in the case that there is no remaining path).
-               """
-               slugs = path.split(pathsep)
-               obj = root
-               remaining_slugs = list(slugs)
-               remainder = None
-               for slug in slugs:
-                       remaining_slugs.remove(slug)
-                       if slug: # ignore blank slugs, handles for multiple consecutive pathseps
-                               try:
-                                       obj = self.get(slug__exact=slug, parent__exact=obj)
-                               except self.model.DoesNotExist:
-                                       if absolute_result:
-                                               obj = None
-                                       remaining_slugs.insert(0, slug)
-                                       remainder = pathsep.join(remaining_slugs)
-                                       break
-               if obj:
-                       if absolute_result:
-                               return obj
-                       else:
-                               return (obj, remainder)
-               raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
-
-
-class TreeModel(models.Model):
-       objects = TreeManager()
-       parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
-       slug = models.SlugField()
-       
-       def get_path(self, pathsep='/', field='slug'):
-               path = getattr(self, field, '?')
-               parent = self.parent
-               while parent:
-                       path = getattr(parent, field, '?') + pathsep + path
-                       parent = parent.parent
-               return path
-       path = property(get_path)
+       def construct_instance(self, **kwargs):
+               """Apply cleaned data from the formfields generated by valid_formfields to oneself."""
+               raise NotImplementedError
        
        def __unicode__(self):
-               return self.path
+               return unicode(self.value)
        
        class Meta:
                abstract = True
-               app_label = 'philo'
 
 
-class TreeEntity(TreeModel, Entity):
-       @property
-       def attributes(self):
-               if self.parent:
-                       return QuerySetMapper(self.attribute_set, passthrough=self.parent.attributes)
-               return super(TreeEntity, self).attributes
-       
-       @property
-       def relationships(self):
-               if self.parent:
-                       return QuerySetMapper(self.relationship_set, passthrough=self.parent.relationships)
-               return super(TreeEntity, self).relationships
-       
-       class Meta:
-               abstract = True
-               app_label = 'philo'
+attribute_value_limiter = ContentTypeSubclassLimiter(AttributeValue)
 
 
-class InheritableTreeEntity(TreeEntity):
-       instance_type = models.ForeignKey(ContentType, editable=False)
+class JSONValue(AttributeValue):
+       value = JSONField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.', default='null', db_index=True)
        
-       def save(self, force_insert=False, force_update=False):
-               if not hasattr(self, 'instance_type_ptr'):
-                       self.instance_type = ContentType.objects.get_for_model(self.__class__)
-               super(InheritableTreeEntity, self).save(force_insert, force_update)
+       def __unicode__(self):
+               return force_unicode(self.value)
        
-       @property
-       def instance(self):
-               try:
-                       return self.instance_type.get_object_for_this_type(id=self.id)
-               except:
-                       return None
+       def value_formfields(self):
+               kwargs = {'initial': self.value_json}
+               field = self._meta.get_field('value')
+               return {field.name: field.formfield(**kwargs)}
        
-       def get_path(self, pathsep='/', field='slug'):
-               path = getattr(self.instance, field, getattr(self.instance, 'slug', '?'))
-               parent = self.parent
-               while parent:
-                       path = getattr(parent.instance, field, getattr(parent.instance, 'slug', '?')) + pathsep + path
-                       parent = parent.parent
-               return path
-       path = property(get_path)
+       def construct_instance(self, **kwargs):
+               field_name = self._meta.get_field('value').name
+               self.set_value(kwargs.pop(field_name, None))
        
-       @property
-       def attributes(self):
-               if self.parent:
-                       return QuerySetMapper(self.instance.attribute_set, passthrough=self.parent.instance.attributes)
-               return QuerySetMapper(self.instance.attribute_set)
-
-       @property
-       def relationships(self):
-               if self.parent:
-                       return QuerySetMapper(self.instance.relationship_set, passthrough=self.parent.instance.relationships)
-               return QuerySetMapper(self.instance.relationship_set)
+       def set_value(self, value):
+               self.value = value
        
        class Meta:
-               abstract = True
                app_label = 'philo'
 
 
-class Node(InheritableTreeEntity):
-       accepts_subpath = False
+class ForeignKeyValue(AttributeValue):
+       content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True)
+       object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True, db_index=True)
+       value = generic.GenericForeignKey()
        
-       def render_to_response(self, request, path=None, subpath=None):
-               return HttpResponseServerError()
+       def value_formfields(self):
+               field = self._meta.get_field('content_type')
+               fields = {field.name: field.formfield(initial=getattr(self.content_type, 'pk', None))}
                
-       class Meta:
-               unique_together = (('parent', 'slug'),)
-               app_label = 'philo'
-
-
-class MultiNode(Node):
-       accepts_subpath = True
+               if self.content_type:
+                       kwargs = {
+                               'initial': self.object_id,
+                               'required': False,
+                               'queryset': self.content_type.model_class()._default_manager.all()
+                       }
+                       fields['value'] = forms.ModelChoiceField(**kwargs)
+               return fields
+       
+       def construct_instance(self, **kwargs):
+               field_name = self._meta.get_field('content_type').name
+               ct = kwargs.pop(field_name, None)
+               if ct is None or ct != self.content_type:
+                       self.object_id = None
+                       self.content_type = ct
+               else:
+                       value = kwargs.pop('value', None)
+                       self.set_value(value)
+                       if value is None:
+                               self.content_type = ct
        
-       urlpatterns = []
-       
-       def render_to_response(self, request, path=None, subpath=None):
-               if not subpath:
-                       subpath = ""
-               subpath = "/" + subpath
-               from django.core.urlresolvers import resolve
-               view, args, kwargs = resolve(subpath, urlconf=self)
-               return view(request, *args, **kwargs)
+       def set_value(self, value):
+               self.value = value
        
        class Meta:
-               abstract = True
                app_label = 'philo'
 
 
-class Redirect(Node):
-       STATUS_CODES = (
-               (302, 'Temporary'),
-               (301, 'Permanent'),
-       )
-       target = models.CharField(max_length=200,validators=[RedirectValidator()])
-       status_code = models.IntegerField(choices=STATUS_CODES, default=302, verbose_name='redirect type')
+class ManyToManyValue(AttributeValue):
+       content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True)
+       values = models.ManyToManyField(ForeignKeyValue, blank=True, null=True)
        
-       def render_to_response(self, request, path=None, subpath=None):
-               response = HttpResponseRedirect(self.target)
-               response.status_code = self.status_code
-               return response
+       def get_object_ids(self):
+               return self.values.values_list('object_id', flat=True)
+       object_ids = property(get_object_ids)
        
-       class Meta:
-               app_label = 'philo'
-
-
-class File(Node):
-       """ For storing arbitrary files """
-       mimetype = models.CharField(max_length=255)
-       file = models.FileField(upload_to='philo/files/%Y/%m/%d')
+       def set_value(self, value):
+               # Value must be a queryset. Watch out for ModelMultipleChoiceField;
+               # it returns its value as a list if empty.
+               
+               self.content_type = ContentType.objects.get_for_model(value.model)
+               
+               # Before we can fiddle with the many-to-many to foreignkeyvalues, we need
+               # a pk.
+               if self.pk is None:
+                       self.save()
+               
+               object_ids = value.values_list('id', flat=True)
+               
+               # These lines shouldn't be necessary; however, if object_ids is an EmptyQuerySet,
+               # the code (specifically the object_id__in query) won't work without them. Unclear why...
+               # TODO: is this still the case?
+               if not object_ids:
+                       self.values.all().delete()
+               else:
+                       self.values.exclude(object_id__in=object_ids, content_type=self.content_type).delete()
+                       
+                       current_ids = self.object_ids
+                       
+                       for object_id in object_ids:
+                               if object_id in current_ids:
+                                       continue
+                               self.values.create(content_type=self.content_type, object_id=object_id)
        
-       def render_to_response(self, request, path=None, subpath=None):
-               wrapper = FileWrapper(self.file)
-               response = HttpResponse(wrapper, content_type=self.mimetype)
-               response['Content-Length'] = self.file.size
-               return response
+       def get_value(self):
+               if self.content_type is None:
+                       return None
+               
+               # HACK to be safely explicit until http://code.djangoproject.com/ticket/15145 is resolved
+               object_ids = self.object_ids
+               manager = self.content_type.model_class()._default_manager
+               if not object_ids:
+                       return manager.none()
+               return manager.filter(id__in=self.object_ids)
+       
+       value = property(get_value, set_value)
+       
+       def value_formfields(self):
+               field = self._meta.get_field('content_type')
+               fields = {field.name: field.formfield(initial=getattr(self.content_type, 'pk', None))}
+               
+               if self.content_type:
+                       kwargs = {
+                               'initial': self.object_ids,
+                               'required': False,
+                               'queryset': self.content_type.model_class()._default_manager.all()
+                       }
+                       fields['value'] = forms.ModelMultipleChoiceField(**kwargs)
+               return fields
+       
+       def construct_instance(self, **kwargs):
+               field_name = self._meta.get_field('content_type').name
+               ct = kwargs.pop(field_name, None)
+               if ct is None or ct != self.content_type:
+                       self.values.clear()
+                       self.content_type = ct
+               else:
+                       value = kwargs.get('value', None)
+                       if not value:
+                               value = self.content_type.model_class()._default_manager.none()
+                       self.set_value(value)
+       construct_instance.alters_data = True
        
        class Meta:
                app_label = 'philo'
 
 
-class Template(TreeModel):
-       name = models.CharField(max_length=255)
-       documentation = models.TextField(null=True, blank=True)
-       mimetype = models.CharField(max_length=255, null=True, blank=True, help_text='Default: %s' % settings.DEFAULT_CONTENT_TYPE)
-       code = models.TextField(verbose_name='django template code')
-       
-       @property
-       def origin(self):
-               return 'philo.models.Template: ' + self.path
+class Attribute(models.Model):
+       entity_content_type = models.ForeignKey(ContentType, related_name='attribute_entity_set', verbose_name='Entity type')
+       entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID', db_index=True)
+       entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
        
-       @property
-       def django_template(self):
-               return DjangoTemplate(self.code)
+       value_content_type = models.ForeignKey(ContentType, related_name='attribute_value_set', limit_choices_to=attribute_value_limiter, verbose_name='Value type', null=True, blank=True)
+       value_object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True, db_index=True)
+       value = generic.GenericForeignKey('value_content_type', 'value_object_id')
        
-       @property
-       def containers(self):
-               """
-               Returns a tuple where the first item is a list of names of contentlets referenced by containers,
-               and the second item is a list of tuples of names and contenttypes of contentreferences referenced by containers.
-               This will break if there is a recursive extends or includes in the template code.
-               Due to the use of an empty Context, any extends or include tags with dynamic arguments probably won't work.
-               """
-               def container_nodes(template):
-                       def nodelist_container_nodes(nodelist):
-                               nodes = []
-                               for node in nodelist:
-                                       try:
-                                               for nodelist_name in ('nodelist', 'nodelist_loop', 'nodelist_empty', 'nodelist_true', 'nodelist_false', 'nodelist_main'):
-                                                       if hasattr(node, nodelist_name):
-                                                               nodes.extend(nodelist_container_nodes(getattr(node, nodelist_name)))
-                                               if isinstance(node, ContainerNode):
-                                                       nodes.append(node)
-                                               elif isinstance(node, ExtendsNode):
-                                                       extended_template = node.get_parent(Context())
-                                                       if extended_template:
-                                                               nodes.extend(container_nodes(extended_template))
-                                               elif isinstance(node, ConstantIncludeNode):
-                                                       included_template = node.template
-                                                       if included_template:
-                                                               nodes.extend(container_nodes(included_template))
-                                               elif isinstance(node, IncludeNode):
-                                                       included_template = get_template(node.template_name.resolve(Context()))
-                                                       if included_template:
-                                                               nodes.extend(container_nodes(included_template))
-                                       except:
-                                               pass # fail for this node
-                               return nodes
-                       return nodelist_container_nodes(template.nodelist)
-               all_nodes = container_nodes(self.django_template)
-               contentlet_node_names = set([node.name for node in all_nodes if not node.references])
-               contentreference_node_names = []
-               contentreference_node_specs = []
-               for node in all_nodes:
-                       if node.references and node.name not in contentreference_node_names:
-                               contentreference_node_specs.append((node.name, node.references))
-                               contentreference_node_names.append(node.name)
-               return contentlet_node_names, contentreference_node_specs
+       key = models.CharField(max_length=255, validators=[RegexValidator("\w+")], help_text="Must contain one or more alphanumeric characters or underscores.", db_index=True)
        
        def __unicode__(self):
-               return self.get_path(u' › ', 'name')
-       
-       @staticmethod
-       @fattr(is_usable=True)
-       def loader(template_name, template_dirs=None): # load_template_source
-               try:
-                       template = Template.objects.get_with_path(template_name)
-               except Template.DoesNotExist:
-                       raise TemplateDoesNotExist(template_name)
-               return (template.code, template.origin)
+               return u'"%s": %s' % (self.key, self.value)
        
        class Meta:
                app_label = 'philo'
+               unique_together = (('key', 'entity_content_type', 'entity_object_id'), ('value_content_type', 'value_object_id'))
 
 
-class Page(Node):
-       """
-       Represents a page - something which is rendered according to a template. The page will have a number of related Contentlets depending on the template selected - but these will appear only after the page has been saved with that template.
-       """
-       template = models.ForeignKey(Template, related_name='pages')
-       title = models.CharField(max_length=255)
+class QuerySetMapper(object, DictMixin):
+       def __init__(self, queryset, passthrough=None):
+               self.queryset = queryset
+               self.passthrough = passthrough
        
-       def render_to_response(self, request, path=None, subpath=None):
-               return HttpResponse(self.template.django_template.render(RequestContext(request, {'page': self})), mimetype=self.template.mimetype)
+       def __getitem__(self, key):
+               try:
+                       value = self.queryset.get(key__exact=key).value
+               except ObjectDoesNotExist:
+                       if self.passthrough is not None:
+                               return self.passthrough.__getitem__(key)
+                       raise KeyError
+               else:
+                       if value is not None:
+                               return value.value
+                       return value
        
-       def __unicode__(self):
-               return self.get_path(u' › ', 'title')
+       def keys(self):
+               keys = set(self.queryset.values_list('key', flat=True).distinct())
+               if self.passthrough is not None:
+                       keys |= set(self.passthrough.keys())
+               return list(keys)
+
+
+class EntityOptions(object):
+       def __init__(self, options):
+               if options is not None:
+                       for key, value in options.__dict__.items():
+                               setattr(self, key, value)
+               if not hasattr(self, 'proxy_fields'):
+                       self.proxy_fields = []
        
-       class Meta:
-               app_label = 'philo'
+       def add_proxy_field(self, proxy_field):
+               self.proxy_fields.append(proxy_field)
 
 
-# the following line enables the selection of a node as the root for a given django.contrib.sites Site object
-models.ForeignKey(Node, related_name='sites', null=True, blank=True).contribute_to_class(Site, 'root_node')
+class EntityBase(models.base.ModelBase):
+       def __new__(cls, name, bases, attrs):
+               entity_meta = attrs.pop('EntityMeta', None)
+               new = super(EntityBase, cls).__new__(cls, name, bases, attrs)
+               new.add_to_class('_entity_meta', EntityOptions(entity_meta))
+               entity_class_prepared.send(sender=new)
+               return new
 
 
-class Contentlet(models.Model):
-       page = models.ForeignKey(Page, related_name='contentlets')
-       name = models.CharField(max_length=255)
-       content = models.TextField()
-       dynamic = models.BooleanField(default=False)
+class Entity(models.Model):
+       __metaclass__ = EntityBase
        
-       def __unicode__(self):
-               return self.name
+       attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
+       
+       @property
+       def attributes(self):
+               return QuerySetMapper(self.attribute_set.all())
        
        class Meta:
-               app_label = 'philo'
+               abstract = True
 
 
-class ContentReference(models.Model):
-       page = models.ForeignKey(Page, related_name='contentreferences')
-       name = models.CharField(max_length=255)
-       content_type = models.ForeignKey(ContentType, verbose_name='Content type')
-       content_id = models.PositiveIntegerField(verbose_name='Content ID', blank=True, null=True)
-       content = generic.GenericForeignKey('content_type', 'content_id')
+class TreeManager(models.Manager):
+       use_for_related_fields = True
+       
+       def get_with_path(self, path, root=None, absolute_result=True, pathsep='/', field='slug'):
+               """
+               Returns the object with the path, unless absolute_result is set to False, in which
+               case it returns a tuple containing the deepest object found along the path, and the
+               remainder of the path after that object as a string (or None if there is no remaining
+               path). Raises a DoesNotExist exception if no object is found with the given path.
+               
+               If the path you're searching for is known to exist, it is always faster to use
+               absolute_result=True - unless the path depth is over ~40, in which case the high cost
+               of the absolute query makes a binary search (i.e. non-absolute) faster.
+               """
+               # Note: SQLite allows max of 64 tables in one join. That means the binary search will
+               # only work on paths with a max depth of 127 and the absolute fetch will only work
+               # to a max depth of (surprise!) 63. Although this could be handled, chances are your
+               # tree structure won't be that deep.
+               segments = path.split(pathsep)
+               
+               # Clean out blank segments. Handles multiple consecutive pathseps.
+               while True:
+                       try:
+                               segments.remove('')
+                       except ValueError:
+                               break
+               
+               # Special-case a lack of segments. No queries necessary.
+               if not segments:
+                       if root is not None:
+                               if absolute_result:
+                                       return root
+                               return root, None
+                       else:
+                               raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
+               
+               def make_query_kwargs(segments, root):
+                       kwargs = {}
+                       prefix = ""
+                       revsegs = list(segments)
+                       revsegs.reverse()
+                       
+                       for segment in revsegs:
+                               kwargs["%s%s__exact" % (prefix, field)] = segment
+                               prefix += "parent__"
+                       
+                       if prefix:
+                               kwargs[prefix[:-2]] = root
+                       
+                       return kwargs
+               
+               def find_obj(segments, depth, deepest_found=None):
+                       if deepest_found is None:
+                               deepest_level = 0
+                       elif root is None:
+                               deepest_level = deepest_found.get_level() + 1
+                       else:
+                               deepest_level = deepest_found.get_level() - root.get_level()
+                       try:
+                               obj = self.get(**make_query_kwargs(segments[deepest_level:depth], deepest_found or root))
+                       except self.model.DoesNotExist:
+                               if not deepest_level and depth > 1:
+                                       # make sure there's a root node...
+                                       depth = 1
+                               else:
+                                       # Try finding one with half the path since the deepest find.
+                                       depth = (deepest_level + depth)/2
+                               
+                               if deepest_level == depth:
+                                       # This should happen if nothing is found with any part of the given path.
+                                       if root is not None and deepest_found is None:
+                                               return root, pathsep.join(segments)
+                                       raise
+                               
+                               return find_obj(segments, depth, deepest_found)
+                       else:
+                               # Yay! Found one!
+                               if root is None:
+                                       deepest_level = obj.get_level() + 1
+                               else:
+                                       deepest_level = obj.get_level() - root.get_level()
+                               
+                               # Could there be a deeper one?
+                               if obj.is_leaf_node():
+                                       return obj, pathsep.join(segments[deepest_level:]) or None
+                               
+                               depth += (len(segments) - depth)/2 or len(segments) - depth
+                               
+                               if depth > deepest_level + obj.get_descendant_count():
+                                       depth = deepest_level + obj.get_descendant_count()
+                               
+                               if deepest_level == depth:
+                                       return obj, pathsep.join(segments[deepest_level:]) or None
+                               
+                               try:
+                                       return find_obj(segments, depth, obj)
+                               except self.model.DoesNotExist:
+                                       # Then this was the deepest.
+                                       return obj, pathsep.join(segments[deepest_level:])
+               
+               if absolute_result:
+                       return self.get(**make_query_kwargs(segments, root))
+               
+               # Try a modified binary search algorithm. Feed the root in so that query complexity
+               # can be reduced. It might be possible to weight the search towards the beginning
+               # of the path, since short paths are more likely, but how far forward? It would
+               # need to shift depending on len(segments) - perhaps logarithmically?
+               return find_obj(segments, len(segments)/2 or len(segments))
+
+
+class TreeModel(MPTTModel):
+       objects = TreeManager()
+       parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
+       slug = models.SlugField(max_length=255)
+       
+       def get_path(self, root=None, pathsep='/', field='slug'):
+               if root == self:
+                       return ''
+               
+               if root is not None and not self.is_descendant_of(root):
+                       raise AncestorDoesNotExist(root)
+               
+               qs = self.get_ancestors(include_self=True)
+               
+               if root is not None:
+                       qs = qs.filter(**{'%s__gt' % self._mptt_meta.level_attr: root.get_level()})
+               
+               return pathsep.join([getattr(parent, field, '?') for parent in qs])
+       path = property(get_path)
        
        def __unicode__(self):
-               return self.name
+               return self.path
        
        class Meta:
-               app_label = 'philo'
+               unique_together = (('parent', 'slug'),)
+               abstract = True
 
 
-register_templatetags('philo.templatetags.containers')
+class TreeEntityBase(MPTTModelBase, EntityBase):
+       def __new__(meta, name, bases, attrs):
+               attrs['_mptt_meta'] = MPTTOptions(attrs.pop('MPTTMeta', None))
+               cls = EntityBase.__new__(meta, name, bases, attrs)
+               
+               return meta.register(cls)
 
 
-register_value_model(User)
-register_value_model(Group)
-register_value_model(Site)
-register_value_model(Collection)
-register_value_model(Template)
-register_value_model(Page)
+class TreeEntity(Entity, TreeModel):
+       __metaclass__ = TreeEntityBase
+       
+       @property
+       def attributes(self):
+               if self.parent:
+                       return QuerySetMapper(self.attribute_set.all(), passthrough=self.parent.attributes)
+               return super(TreeEntity, self).attributes
+       
+       class Meta:
+               abstract = True
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