5 files changed, 17 insertions, 20 deletions
diff --git a/rest_framework/utils/encoders.py b/rest_framework/utils/encoders.py
index 2c97f1d7..0bd24939 100644
--- a/rest_framework/utils/encoders.py
+++ b/rest_framework/utils/encoders.py
@@ -4,8 +4,8 @@ Helper classes for parsers.
 from __future__ import unicode_literals
 from django.db.models.query import QuerySet
 from django.utils import six, timezone
+from django.utils.encoding import force_text
 from django.utils.functional import Promise
-from rest_framework.compat import force_text
 import datetime
 import decimal
 import json
diff --git a/rest_framework/utils/field_mapping.py b/rest_framework/utils/field_mapping.py
index 9c187176..fca97b4b 100644
--- a/rest_framework/utils/field_mapping.py
+++ b/rest_framework/utils/field_mapping.py
@@ -59,7 +59,7 @@ def get_field_kwargs(field_name, model_field):
     Creates a default instance of a basic non-relational field.
     """
     kwargs = {}
-    validator_kwarg = model_field.validators
+    validator_kwarg = list(model_field.validators)
 
     # The following will only be used by ModelField classes.
     # Gets removed for everything else.
@@ -91,18 +91,18 @@ def get_field_kwargs(field_name, model_field):
     if model_field.has_default() or model_field.blank or model_field.null:
         kwargs['required'] = False
 
-    if model_field.flatchoices:
-        # If this model field contains choices, then return early.
-        # Further keyword arguments are not valid.
-        kwargs['choices'] = model_field.flatchoices
-        return kwargs
-
     if model_field.null and not isinstance(model_field, models.NullBooleanField):
         kwargs['allow_null'] = True
 
     if model_field.blank:
         kwargs['allow_blank'] = True
 
+    if model_field.flatchoices:
+        # If this model field contains choices, then return early.
+        # Further keyword arguments are not valid.
+        kwargs['choices'] = model_field.flatchoices
+        return kwargs
+
     # Ensure that max_length is passed explicitly as a keyword arg,
     # rather than as a validator.
     max_length = getattr(model_field, 'max_length', None)
diff --git a/rest_framework/utils/mediatypes.py b/rest_framework/utils/mediatypes.py
index 87b3cc6a..de2931c2 100644
--- a/rest_framework/utils/mediatypes.py
+++ b/rest_framework/utils/mediatypes.py
@@ -5,6 +5,7 @@ See http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7
 """
 from __future__ import unicode_literals
 from django.http.multipartparser import parse_header
+from django.utils.encoding import python_2_unicode_compatible
 from rest_framework import HTTP_HEADER_ENCODING
 
 
@@ -43,6 +44,7 @@ def order_by_precedence(media_type_lst):
     return [media_types for media_types in ret if media_types]
 
 
+@python_2_unicode_compatible
 class _MediaType(object):
     def __init__(self, media_type_str):
         if media_type_str is None:
@@ -79,9 +81,6 @@ class _MediaType(object):
         return 3
 
     def __str__(self):
-        return self.__unicode__().encode('utf-8')
-
-    def __unicode__(self):
         ret = "%s/%s" % (self.main_type, self.sub_type)
         for key, val in self.params.items():
             ret += "; %s=%s" % (key, val)
diff --git a/rest_framework/utils/representation.py b/rest_framework/utils/representation.py
index 2a7c4675..3f17a8b9 100644
--- a/rest_framework/utils/representation.py
+++ b/rest_framework/utils/representation.py
@@ -3,8 +3,8 @@ Helper functions for creating user-friendly representations
 of serializer classes and serializer fields.
 """
 from django.db import models
+from django.utils.encoding import force_text
 from django.utils.functional import Promise
-from rest_framework.compat import force_text
 import re
 
 
diff --git a/rest_framework/utils/serializer_helpers.py b/rest_framework/utils/serializer_helpers.py
index 92d19857..277cf649 100644
--- a/rest_framework/utils/serializer_helpers.py
+++ b/rest_framework/utils/serializer_helpers.py
@@ -1,3 +1,4 @@
+import collections
 from rest_framework.compat import OrderedDict
 
 
@@ -70,7 +71,7 @@ class NestedBoundField(BoundField):
         return BoundField(field, value, error, prefix=self.name + '.')
 
 
-class BindingDict(object):
+class BindingDict(collections.MutableMapping):
     """
     This dict-like object is used to store fields on a serializer.
 
@@ -92,11 +93,8 @@ class BindingDict(object):
     def __delitem__(self, key):
         del self.fields[key]
 
-    def items(self):
-        return self.fields.items()
-
-    def keys(self):
-        return self.fields.keys()
+    def __iter__(self):
+        return iter(self.fields)
 
-    def values(self):
-        return self.fields.values()
+    def __len__(self):
+        return len(self.fields)