add Section.get_tree_depth

CHANGES.txt

@@ -1,3 +1,8 @@
+1.2.4
+==================
+
+* Added `Section.get_tree_depth()`
+
 1.2.3 (2016-09-09)
 ==================
 

pagetree/models.py

@@ -192,6 +192,7 @@ def clear_caches(self):
         cache.delete("pagetree.%d.get_absolute_url" % self.id)
         cache.delete("pagetree.%d.is_last_child" % self.id)
         cache.delete("pagetree.%d.get_edit_url" % self.id)
+        cache.delete("pagetree.%d.get_tree_depth" % self.id)
 
         if hasattr(settings, 'PAGETREE_CUSTOM_CACHE_CLEAR') and \
            callable(settings.PAGETREE_CUSTOM_CACHE_CLEAR):
@@ -665,6 +666,17 @@ def clone(original, section):
 
         return section
 
+    def get_tree_depth(self):
+        key = 'pagetree.{}.get_tree_depth'.format(self.pk)
+        v = cache.get(key)
+        if v is not None:
+            return v
+
+        for idx, sec in enumerate(self.get_tree()):
+            if sec == self:
+                cache.set(key, idx)
+                return idx
+
 
 @python_2_unicode_compatible
 class PageBlock(models.Model):

pagetree/tests/test_models.py

@@ -304,6 +304,11 @@ def test_update_children_order(self):
         r = self.root.get_children()
         self.assertEqual([s.id for s in r], normal_order)
 
+    def test_get_tree_depth(self):
+        self.assertEqual(self.section1.get_tree_depth(), 1)
+        self.assertEqual(self.section2.get_tree_depth(), 2)
+        self.assertEqual(self.section3.get_tree_depth(), 3)
+
 
 class OneLevelWithBlocksTest(unittest.TestCase):
     def setUp(self):