From 3873bc8a857829a12b2bb6a34610ab5295887660 Mon Sep 17 00:00:00 2001
From: Yuri Prezument <y@yprez.com>
Date: Wed, 2 Jan 2013 15:55:35 +0200
Subject: [PATCH] Add explaining comment

---
 rest_framework/fields.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 47bdc26aa..5ae8ff485 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -191,6 +191,8 @@ class WritableField(Field):
         except KeyError:
             if self.default is not None and not self.root.partial:
                 native = self.default
+                # partial serializers shouldn't set the default field to avoid
+                # overriding the previously set value
             else:
                 if self.required:
                     raise ValidationError(self.error_messages['required'])