From 488b13e7b8591f667a01c01f3f0aa09749627831 Mon Sep 17 00:00:00 2001
From: Tom Christie
Date: Mon, 15 Dec 2014 09:29:54 +0000
Subject: Better messaging for 'Field.to_representation'. Closes #2271.

---
 rest_framework/fields.py | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 205efd2f..21a1effd 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -382,13 +382,23 @@ class Field(object):
         """
         Transform the *incoming* primitive data into a native value.
         """
-        raise NotImplementedError('to_internal_value() must be implemented.')
+        raise NotImplementedError(
+            '{cls}.to_internal_value() must be implemented.'.format(
+                cls=self.__class__.__name__
+            )
+        )
 
     def to_representation(self, value):
         """
         Transform the *outgoing* native value into primitive data.
         """
-        raise NotImplementedError('to_representation() must be implemented.')
+        raise NotImplementedError(
+            '{cls}.to_representation() must be implemented.\n'
+            'If you are upgrading from REST framework version 2 '
+            'you might want `ReadOnlyField`.'.format(
+                cls=self.__class__.__name__
+            )
+        )
 
     def fail(self, key, **kwargs):
         """
-- 
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