1 files changed, 24 insertions, 7 deletions
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 58482db5..ca9c479f 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -68,8 +68,8 @@ def get_attribute(instance, attrs):
                 return instance[attr]
             except (KeyError, TypeError, AttributeError):
                 raise exc
-    if is_simple_callable(instance):
-        return instance()
+        if is_simple_callable(instance):
+            instance = instance()
     return instance
 
 
@@ -117,6 +117,17 @@ class CreateOnlyDefault:
         return '%s(%s)' % (self.__class__.__name__, repr(self.default))
 
 
+class CurrentUserDefault:
+    def set_context(self, serializer_field):
+        self.user = serializer_field.context['request'].user
+
+    def __call__(self):
+        return self.user
+
+    def __repr__(self):
+        return '%s()' % self.__class__.__name__
+
+
 class SkipField(Exception):
     pass
 
@@ -170,6 +181,9 @@ class Field(object):
         self.style = {} if style is None else style
         self.allow_null = allow_null
 
+        if allow_null and self.default_empty_html is empty:
+            self.default_empty_html = None
+
         if validators is not None:
             self.validators = validators[:]
 
@@ -248,7 +262,11 @@ class Field(object):
         if html.is_html_input(dictionary):
             # HTML forms will represent empty fields as '', and cannot
             # represent None or False values directly.
-            ret = dictionary.get(self.field_name, '')
+            if self.field_name not in dictionary:
+                if getattr(self.root, 'partial', False):
+                    return empty
+                return self.default_empty_html
+            ret = dictionary[self.field_name]
             return self.default_empty_html if (ret == '') else ret
         return dictionary.get(self.field_name, empty)
 
@@ -303,7 +321,6 @@ class Field(object):
 
         value = self.to_internal_value(data)
         self.run_validators(value)
-        self.validate(value)
         return value
 
     def run_validators(self, value):
@@ -330,9 +347,6 @@ class Field(object):
         if errors:
             raise ValidationError(errors)
 
-    def validate(self, value):
-        pass
-
     def to_internal_value(self, data):
         """
         Transform the *incoming* primitive data into a native value.
@@ -484,6 +498,7 @@ class CharField(Field):
     }
     initial = ''
     coerce_blank_to_null = False
+    default_empty_html = ''
 
     def __init__(self, **kwargs):
         self.allow_blank = kwargs.pop('allow_blank', False)
@@ -936,6 +951,8 @@ class ChoiceField(Field):
             self.fail('invalid_choice', input=data)
 
     def to_representation(self, value):
+        if value in ('', None):
+            return value
         return self.choice_strings_to_values[six.text_type(value)]