Unexpected behaviour of validate() in BinaryField, DecimalField and UrlField

motorengine/fields/binary_field.py

@@ -26,18 +26,27 @@ def __init__(self, max_bytes=None, *args, **kwargs):
         self.max_bytes = max_bytes
 
     def to_son(self, value):
+        if value is None:
+            return None
+
         if not isinstance(value, (six.binary_type, )):
             return six.b(value)
 
         return value
 
     def from_son(self, value):
+        if value is None:
+            return None
+
         if not isinstance(value, (six.binary_type, )):
             return six.b(value)
 
         return value
 
     def validate(self, value):
+        if value is None:
+            return True
+
         if not isinstance(value, (six.binary_type, )):
             return False
 

motorengine/fields/decimal_field.py

@@ -55,15 +55,24 @@ def __init__(self, min_value=None, max_value=None, precision=2, rounding=decimal
         self.rounding = rounding
 
     def to_son(self, value):
+        if value is None:
+            return None
+
         value = decimal.Decimal(value)
         return six.u(str(value.quantize(self.precision, rounding=self.rounding)))
 
     def from_son(self, value):
+        if value is None:
+            return None
+
         value = decimal.Decimal(value)
 
         return value.quantize(self.precision, rounding=self.rounding)
 
     def validate(self, value):
+        if value is None:
+            return True
+
         try:
             value = decimal.Decimal(value)
         except:

motorengine/fields/url_field.py

@@ -34,6 +34,9 @@ class URLField(BaseField):
     )
 
     def validate(self, value):
+        if value is None:
+            return True
+
         is_url = URLField.URL_REGEX.match(value)
 
         return is_url