Break backwards compat: ValidationError.path is now in sorted order.

docs/creating.rst

@@ -15,5 +15,6 @@ Creating Validation Errors
 --------------------------
 
 Any validating function that recurses into an instance (e.g. ``properties`` or
-``items``) must append to the :exc:`ValidationError.path` attribute of the
-error in order to properly maintain where in the instance the error occurred.
+``items``) must call ``appendleft`` on the :exc:`ValidationError.path`
+attribute of the error in order to properly maintain where in the instance the
+error occurred.

docs/errors.rst

@@ -21,8 +21,8 @@ raised or returned, depending on which method or function is used.
 
     .. attribute:: path
 
-        A list containing the path to the offending element (or [] if the error
-        happened globally) in *reverse* order (i.e. deepest index first).
+        A deque containing the path to the offending element (or an empty deque
+        if the error happened globally).
 
 
 In case an invalid schema itself is encountered, a :exc:`SchemaError` is

jsonschema.py

@@ -55,7 +55,7 @@ class _Error(Exception):
     def __init__(self, message, validator=None, path=()):
         super(_Error, self).__init__(message, validator, path)
         self.message = message
-        self.path = list(path)
+        self.path = collections.deque(path)
         self.validator = validator
 
     def __str__(self):
@@ -202,12 +202,12 @@ class _Draft34CommonMixin(object):
         if self.is_type(items, "object"):
             for index, item in enumerate(instance):
                 for error in self.iter_errors(item, items):
-                    error.path.append(index)
+                    error.path.appendleft(index)
                     yield error
         else:
             for (index, item), subschema in zip(enumerate(instance), items):
                 for error in self.iter_errors(item, subschema):
-                    error.path.append(index)
+                    error.path.appendleft(index)
                     yield error
 
     def validate_additionalItems(self, aI, instance, schema):
@@ -366,7 +366,7 @@ class Draft3Validator(ValidatorMixin, _Draft34CommonMixin, object):
         for property, subschema in iteritems(properties):
             if property in instance:
                 for error in self.iter_errors(instance[property], subschema):
-                    error.path.append(property)
+                    error.path.appendleft(property)
                     yield error
             elif subschema.get("required", False):
                 yield ValidationError(
@@ -495,7 +495,7 @@ class Draft4Validator(ValidatorMixin, _Draft34CommonMixin, object):
         for property, subschema in iteritems(properties):
             if property in instance:
                 for error in self.iter_errors(instance[property], subschema):
-                    error.path.append(property)
+                    error.path.appendleft(property)
                     yield error
 
     def validate_required(self, required, instance, schema):
@@ -1054,7 +1054,7 @@ class ErrorTree(object):
 
         for error in errors:
             container = self
-            for element in reversed(error.path):
+            for element in error.path:
                 container = container[element]
             container.errors[error.validator] = error
 

tests.py

@@ -365,10 +365,10 @@ class TestValidationErrorDetails(unittest.TestCase):
         errors = self.validator.iter_errors(instance, schema)
         e1, e2, e3, e4 = sorted_errors(errors)
 
-        self.assertEqual(e1.path, ["bar"])
-        self.assertEqual(e2.path, ["baz"])
-        self.assertEqual(e3.path, ["baz"])
-        self.assertEqual(e4.path, ["foo"])
+        self.assertItemsEqual(e1.path, ["bar"])
+        self.assertItemsEqual(e2.path, ["baz"])
+        self.assertItemsEqual(e3.path, ["baz"])
+        self.assertItemsEqual(e4.path, ["foo"])
 
         self.assertEqual(e1.validator, "minItems")
         self.assertEqual(e2.validator, "enum")
@@ -397,12 +397,12 @@ class TestValidationErrorDetails(unittest.TestCase):
         errors = self.validator.iter_errors(instance, schema)
         e1, e2, e3, e4, e5, e6 = sorted_errors(errors)
 
-        self.assertEqual(e1.path, [])
-        self.assertEqual(e2.path, [0])
-        self.assertEqual(e3.path, ["bar", 1])
-        self.assertEqual(e4.path, ["bar", "bar", 1])
-        self.assertEqual(e5.path, ["baz", "bar", 1])
-        self.assertEqual(e6.path, ["foo", 1])
+        self.assertItemsEqual(e1.path, [])
+        self.assertItemsEqual(e2.path, [0])
+        self.assertItemsEqual(e3.path, [1, "bar"])
+        self.assertItemsEqual(e4.path, [1, "bar", "bar"])
+        self.assertItemsEqual(e5.path, [1, "bar", "baz"])
+        self.assertItemsEqual(e6.path, [1, "foo"])
 
         self.assertEqual(e1.validator, "type")
         self.assertEqual(e2.validator, "type")
@@ -439,7 +439,7 @@ class TestErrorTree(unittest.TestCase):
     def test_it_creates_a_child_tree_for_each_nested_path(self):
         errors = [
             ValidationError("a bar message", path=["bar"]),
-            ValidationError("a bar -> 0 message", path=[0, "bar"]),
+            ValidationError("a bar -> 0 message", path=["bar", 0]),
         ]
         tree = ErrorTree(errors)
         self.assertIn(0, tree["bar"])
@@ -447,8 +447,8 @@ class TestErrorTree(unittest.TestCase):
 
     def test_children_have_their_errors_dicts_built(self):
         e1, e2 = (
-            ValidationError("message 1", validator="foo", path=[0, "bar"]),
-            ValidationError("message 2", validator="quux", path=[0, "bar"]),
+            ValidationError("message 1", validator="foo", path=["bar", 0]),
+            ValidationError("message 2", validator="quux", path=["bar", 0]),
         )
         tree = ErrorTree([e1, e2])
         self.assertEqual(tree["bar"][0].errors, {"foo" : e1, "quux" : e2})