Solves issue#59 - Treat None values as non-existing keys for default_…

…box (#108)

* Solves issue#59 - Treat None values as non-existing keys for default_box

AUTHORS.rst

@@ -16,6 +16,7 @@ Code contributions:
 - Brandon Gomes (bhgomes)
 - Stretch (str3tch)
 - (pwwang)
+- Harun Tuncay (haruntuncay)
 
 Suggestions and bug reporting:
 

box/box.py

@@ -147,6 +147,7 @@ class Box(dict):
     :param default_box: Similar to defaultdict, return a default value
     :param default_box_attr: Specify the default replacement.
         WARNING: If this is not the default 'Box', it will not be recursive
+    :param default_box_none_transform: When using default_box, treat keys with none values as absent. True by default
     :param frozen_box: After creation, the box cannot be modified
     :param camel_killer_box: Convert CamelCase to snake_case
     :param conversion_box: Check for near matching keys as attributes
@@ -159,8 +160,8 @@ class Box(dict):
 
     _protected_keys = dir({}) + ['to_dict', 'to_json', 'to_yaml', 'from_yaml', 'from_json', 'from_toml', 'to_toml']
 
-    def __new__(cls, *args: Any, box_it_up: bool = False, default_box: bool = False,
-                default_box_attr: Any = None, frozen_box: bool = False, camel_killer_box: bool = False,
+    def __new__(cls, *args: Any, box_it_up: bool = False, default_box: bool = False, default_box_attr: Any = None,
+                default_box_none_transform: bool = True, frozen_box: bool = False, camel_killer_box: bool = False,
                 conversion_box: bool = True, modify_tuples_box: bool = False, box_safe_prefix: str = 'x',
                 box_duplicates: str = 'ignore', box_intact_types: Union[Tuple, List] = (), **kwargs: Any):
         """
@@ -172,6 +173,7 @@ def __new__(cls, *args: Any, box_it_up: bool = False, default_box: bool = False,
         obj._box_config.update({
             'default_box': default_box,
             'default_box_attr': default_box_attr or cls.__class__,
+            'default_box_none_transform': default_box_none_transform,
             'conversion_box': conversion_box,
             'box_safe_prefix': box_safe_prefix,
             'frozen_box': frozen_box,
@@ -182,15 +184,16 @@ def __new__(cls, *args: Any, box_it_up: bool = False, default_box: bool = False,
         })
         return obj
 
-    def __init__(self, *args: Any, box_it_up: bool = False, default_box: bool = False,
-                 default_box_attr: Any = None, frozen_box: bool = False, camel_killer_box: bool = False,
+    def __init__(self, *args: Any, box_it_up: bool = False, default_box: bool = False, default_box_attr: Any = None,
+                 default_box_none_transform: bool = True, frozen_box: bool = False, camel_killer_box: bool = False,
                  conversion_box: bool = True, modify_tuples_box: bool = False, box_safe_prefix: str = 'x',
                  box_duplicates: str = 'ignore', box_intact_types: Union[Tuple, List] = (), **kwargs: Any):
         super(Box, self).__init__()
         self._box_config = _get_box_config(kwargs.pop('__box_heritage', None))
         self._box_config.update({
             'default_box': default_box,
             'default_box_attr': default_box_attr or self.__class__,
+            'default_box_none_transform': default_box_none_transform,
             'conversion_box': conversion_box,
             'box_safe_prefix': box_safe_prefix,
             'frozen_box': frozen_box,
@@ -208,6 +211,8 @@ def __init__(self, *args: Any, box_it_up: bool = False, default_box: bool = Fals
                 for k, v in args[0].items():
                     if v is args[0]:
                         v = self
+                    if v is None and self._box_config['default_box'] and self._box_config['default_box_none_transform']:
+                        continue
                     self[k] = v
             elif isinstance(args[0], Iterable):
                 for k, v in args[0]:

box/converters.py

@@ -14,7 +14,8 @@
 
 BOX_PARAMETERS = ('default_box', 'default_box_attr', 'conversion_box',
                   'frozen_box', 'camel_killer_box', 'box_it_up',
-                  'box_safe_prefix', 'box_duplicates', 'ordered_box')
+                  'box_safe_prefix', 'box_duplicates', 'ordered_box',
+                  'default_box_none_transform')
 
 
 def _exists(filename, create=False):

test/test_box.py

@@ -384,6 +384,20 @@ def test_default_box(self):
         bx3 = Box(default_box=True, default_box_attr=3)
         assert bx3.hello == 3
 
+    # Issue#59 https://github.com/cdgriffith/Box/issues/59 "Treat None values as non existing keys for default_box"
+    def test_default_box_none_transforms(self):
+        bx4 = Box({"noneValue": None, "inner": {"noneInner": None}}, default_box=True, default_box_attr="issue#59")
+        assert bx4.noneValue == "issue#59"
+        assert bx4.inner.noneInner == "issue#59"
+
+        bx5 = Box({"noneValue": None, "inner": {"noneInner": None}},
+                  default_box=True,
+                  default_box_none_transform=False,
+                  default_box_attr="attr")
+        assert bx5.noneValue is None
+        assert bx5.absentKey == "attr"
+        assert bx5.inner.noneInner is None
+
     def test_camel_killer_box(self):
         td = extended_test_dict.copy()
         td['CamelCase'] = 'Item'