- Fix apparent failures when calling ``pyramid.traversal.find_model(root,

  path)`` or ``pyramid.traversal.traverse(path)`` when ``path`` is
  (erroneously) a Unicode object. The user is meant to pass these APIs a
  string object, never a Unicode object.  In practice, however, users indeed
  pass Unicode.  Because the string that is passed must be ASCII encodeable,
  now, if they pass a Unicode object, its data is eagerly converted to an
  ASCII string rather than being passed along to downstream code as a
  convenience to the user and to prevent puzzling second-order failures from
  cropping up (all failures will occur within ``pyramid.traversal.traverse``
  rather than later down the line as the result of calling
  ``traversal_path``).

3 files changed, 50 insertions, 1 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 14b2c569d..0720034b2 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -28,6 +28,18 @@ Bug Fixes
 - The ``pyramid_alchemy`` paster template had a typo, preventing an import
   from working.
 
+- Fix apparent failures when calling ``pyramid.traversal.find_model(root,
+  path)`` or ``pyramid.traversal.traverse(path)`` when ``path`` is
+  (erroneously) a Unicode object. The user is meant to pass these APIs a
+  string object, never a Unicode object.  In practice, however, users indeed
+  pass Unicode.  Because the string that is passed must be ASCII encodeable,
+  now, if they pass a Unicode object, its data is eagerly converted to an
+  ASCII string rather than being passed along to downstream code as a
+  convenience to the user and to prevent puzzling second-order failures from
+  cropping up (all failures will occur within ``pyramid.traversal.traverse``
+  rather than later down the line as the result of calling
+  ``traversal_path``).
+
 Backwards Incompatibilities
 ---------------------------
 
diff --git a/pyramid/tests/test_traversal.py b/pyramid/tests/test_traversal.py
index 2deb5982c..3245d6302 100644
--- a/pyramid/tests/test_traversal.py
+++ b/pyramid/tests/test_traversal.py
@@ -522,6 +522,32 @@ class FindModelTests(unittest.TestCase):
         self.assertEqual(root.wascontext, True)
         self.assertEqual(root.request.environ['PATH_INFO'], '/')
 
+    def test_absolute_unicode_found(self):
+        # test for bug wiggy found in wild, traceback stack:
+        # root = u'/%E6%B5%81%E8%A1%8C%E8%B6%8B%E5%8A%BF'
+        # wiggy's code: section=find_model(page, root)
+        # find_model L76: D = traverse(model, path)
+        # traverse L291: return traverser(request)
+        # __call__ line 568: vpath_tuple = traversal_path(vpath)
+        # lru_cached line 91: f(*arg)
+        # traversal_path line 443: path.encode('ascii')
+        # UnicodeEncodeError: 'ascii' codec can't encode characters in
+        #     position 1-12: ordinal not in range(128)
+        #
+        # solution: encode string to ascii in pyramid.traversal.traverse
+        # before passing it along to webob as path_info
+        from pyramid.traversal import ModelGraphTraverser
+        unprintable = DummyContext()
+        root = DummyContext(unprintable)
+        unprintable.__parent__ = root
+        unprintable.__name__ = unicode(
+            '/\xe6\xb5\x81\xe8\xa1\x8c\xe8\xb6\x8b\xe5\x8a\xbf', 'utf-8')
+        root.__parent__ = None
+        root.__name__ = None
+        traverser = ModelGraphTraverser
+        self._registerTraverser(traverser)
+        result = self._callFUT(root, u'/%E6%B5%81%E8%A1%8C%E8%B6%8B%E5%8A%BF')
+        self.assertEqual(result, unprintable)
 
 class ModelPathTests(unittest.TestCase):
     def _callFUT(self, model, *elements):
diff --git a/pyramid/traversal.py b/pyramid/traversal.py
index e928c33f7..fb73ad906 100644
--- a/pyramid/traversal.py
+++ b/pyramid/traversal.py
@@ -228,7 +228,7 @@ def traverse(model, path):
     object supplied to the function as the ``model`` argument.  If an
     empty string is passed as ``path``, the ``model`` passed in will
     be returned.  Model path strings must be escaped in the following
-    manner: each Unicode path segment must be encoded as UTF-8 and as
+    manner: each Unicode path segment must be encoded as UTF-8 and
     each path segment must escaped via Python's :mod:`urllib.quote`.
     For example, ``/path/to%20the/La%20Pe%C3%B1a`` (absolute) or
     ``to%20the/La%20Pe%C3%B1a`` (relative).  The
@@ -272,6 +272,17 @@ def traverse(model, path):
         else:
             path = ''
 
+    # The user is supposed to pass us a string object, never Unicode.  In
+    # practice, however, users indeed pass Unicode to this API.  If they do
+    # pass a Unicode object, its data *must* be entirely encodeable to ASCII,
+    # so we encode it here as a convenience to the user and to prevent
+    # second-order failures from cropping up (all failures will occur at this
+    # step rather than later down the line as the result of calling
+    # ``traversal_path``).
+
+    if isinstance(path, unicode):
+        path = path.encode('ascii')
+
     if path and path[0] == '/':
         model = find_root(model)