From 3544655f02b2bdffe4d101d03f2f1ee22e8dade3 Mon Sep 17 00:00:00 2001
From: Stephen Burrows <stephen.r.burrows@gmail.com>
Date: Thu, 23 Dec 2010 12:04:11 -0500
Subject: [PATCH] Moved NavigationManager cache handling into custom methods
 for better readability and compartmentalization. Added NavigationManager to
 Navigation model. Tweaked navigation generation filter to work based on a
 Node instead of roots.

---
 contrib/navigation/models.py                  | 53 +++++++++++++------
 contrib/navigation/templatetags/navigation.py |  3 +-
 2 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/contrib/navigation/models.py b/contrib/navigation/models.py
index 47e5357..40f8c07 100644
--- a/contrib/navigation/models.py
+++ b/contrib/navigation/models.py
@@ -2,7 +2,7 @@
 from django.core.exceptions import ValidationError
 from django.core.urlresolvers import NoReverseMatch
 from django.db import models
-from philo.models import TreeEntity, JSONField, Node
+from philo.models import TreeEntity, JSONField, Node, TreeManager
 from philo.validators import RedirectValidator
 
 #from mptt.templatetags.mptt_tags import cache_tree_children
@@ -11,7 +11,7 @@ from philo.validators import RedirectValidator
 DEFAULT_NAVIGATION_DEPTH = 3
 
 
-class NavigationManager(models.Manager):
+class NavigationManager(TreeManager):
 	
 	# Analagous to contenttypes, cache Navigation to avoid repeated lookups all over the place.
 	# Navigation will probably be used frequently.
@@ -26,9 +26,8 @@ class NavigationManager(models.Manager):
 		
 		TODO: Should this create the auto-generated navigation in "physical" form?
 		"""
-		key = node.pk
 		try:
-			hosted_navigation = self.__class__._cache[self.db][key]
+			return self._get_from_cache(self.db, node)
 		except KeyError:
 			# Find the most recent host!
 			ancestors = node.get_ancestors(ascending=True, include_self=True).annotate(num_navigation=models.Count("hosted_navigation"))
@@ -36,29 +35,48 @@ class NavigationManager(models.Manager):
 			# Iterate down the ancestors until you find one that:
 			# a) is cached, or
 			# b) has hosted navigation.
-			pks_to_cache = []
+			nodes_to_cache = []
 			host_node = None
 			for ancestor in ancestors:
-				if ancestor.pk in self.__class__._cache[self.db] or ancestor.num_navigation > 0:
+				if self._is_cached(self.db, ancestor) or ancestor.num_navigation > 0:
 					host_node = ancestor
 					break
 				else:
-					pks_to_cache.append(ancestor.pk)
-			
-			if host_node is None:
-				return self.none()
-			
-			if ancestor.pk not in self.__class__._cache[self.db]:
-				self.__class__._cache[self.db][ancestor.pk] = host_node.hosted_navigation.select_related('target_node')
+					nodes_to_cache.append(ancestor)
 			
-			hosted_navigation = self.__class__._cache[self.db][ancestor.pk]
+			if not self._is_cached(self.db, host_node):
+				self._add_to_cache(self.db, host_node)
 			
-			# Cache the queryset instance for every pk that was passed over, as well.
-			for pk in pks_to_cache:
-				self.__class__._cache[self.db][pk] = hosted_navigation
+			# Cache the queryset instance for every node that was passed over, as well.
+			hosted_navigation = self._get_from_cache(self.db, host_node)
+			for node in nodes_to_cache:
+				self._add_to_cache(self.db, node, hosted_navigation)
 		
 		return hosted_navigation
 	
+	def _add_to_cache(self, using, node, qs=None):
+		if node is None or node.pk is None:
+			qs = self.none()
+			key = None
+		else:
+			key = node.pk
+		
+		if qs is None:
+			qs = node.hosted_navigation.select_related('target_node')
+		
+		self.__class__._cache.setdefault(using, {})[key] = qs
+	
+	def _get_from_cache(self, using, node):
+		key = node.pk
+		return self.__class__._cache[self.db][key]
+	
+	def _is_cached(self, using, node):
+		try:
+			self._get_from_cache(using, node)
+		except KeyError:
+			return False
+		return True
+	
 	def clear_cache(self, navigation=None):
 		"""
 		Clear out the navigation cache. This needs to happen during database flushes
@@ -86,6 +104,7 @@ class NavigationManager(models.Manager):
 
 
 class Navigation(TreeEntity):
+	objects = NavigationManager()
 	text = models.CharField(max_length=50)
 	
 	hosting_node = models.ForeignKey(Node, blank=True, null=True, related_name='hosted_navigation', help_text="Be part of this node's root navigation.")
diff --git a/contrib/navigation/templatetags/navigation.py b/contrib/navigation/templatetags/navigation.py
index 9cd9df5..c74891b 100644
--- a/contrib/navigation/templatetags/navigation.py
+++ b/contrib/navigation/templatetags/navigation.py
@@ -7,7 +7,8 @@ register = template.Library()
 
 
 @register.filter
-def get_descendants(roots):
+def get_navigation(node):
+	roots = Navigation.objects.for_node(node)
 	qs = None
 	for root in roots:
 		root_qs = root.get_descendants(include_self=True).complex_filter({'%s__lte' % root._mptt_meta.level_attr: root.get_level() + root.depth}).exclude(depth__isnull=True)
-- 
2.20.1