normalizers: Handle None properly in all normalizers

[etc/taskwarrior.git] / tasklib / task.py

diff --git a/tasklib/task.py b/tasklib/task.py
index 17af8d4977eaaea69f99e2b7608b53b2851e0cbc..789e4efd511359ab473d48ee96f0cc99ea8d63a3 100644 (file)
--- a/tasklib/task.py
+++ b/tasklib/task.py
@@ -52,9 +52,6 @@ class ReadOnlyDictView(object):
     def get(self, key, default=None):
         return copy.deepcopy(self.viewed_dict.get(key, default))
 
-    def has_key(self, key):
-        return self.viewed_dict.has_key(key)
-
     def items(self):
         return [copy.deepcopy(v) for v in self.viewed_dict.items()]
 
@@ -78,6 +75,15 @@ class SerializingObject(object):
         not export empty-valued attributes) if the attribute
         is not iterable (e.g. list or set), in which case
         a empty iterable should be used.
+
+    Normalizing methods should hold the following contract:
+      - They are used to validate and normalize the user input.
+        Any attribute value that comes from the user (during Task
+        initialization, assignign values to Task attributes, or
+        filtering by user-provided values of attributes) is first
+        validated and normalized using the normalize_{key} method.
+      - If validation or normalization fails, normalizer is expected
+        to raise ValueError.
     """
 
     def _deserialize(self, key, value):
@@ -97,6 +103,10 @@ class SerializingObject(object):
         or entered as a value of Task attribute.
         """
 
+        # None value should not be converted by normalizer
+        if value is None:
+            return None
+
         normalize_func = getattr(self, 'normalize_{0}'.format(key),
                                  lambda x: x)
 
@@ -227,7 +237,7 @@ class SerializingObject(object):
             # If the value is already localized, there is no need to change
             # time zone at this point. Also None is a valid value too.
             localized = value
-        
+
         return localized
 
     def normalize_uuid(self, value):