change SortedDict to OrderedDict + fix list and tuple concatination

rest_framework/compat.py

@@ -265,3 +265,30 @@ def python_2_unicode_compatible(klass):
         klass.__unicode__ = klass.__str__
         klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
         return klass
+
+"""
+SortedDict deprecated since django 1.8. There is collections.OrderedDict
+which available since python 2.7 and python 3.1. There are no need of other
+checks because of django 1.7+ requires python 2.7+
+"""
+try:
+    from collections import OrderedDict as SortedDict
+except ImportError:
+    from django.utils.datastructures import SortedDict
+
+"""
+GenericForeignKey moves from generic to fields in django 1.9 and in 1.8 shows
+deprecation warnings
+"""
+if django.VERSION >= (1, 8):
+    from django.contrib.contenttypes.fields import GenericForeignKey
+else:
+    from django.contrib.contenttypes.generic import GenericForeignKey
+
+"""
+django.utils.importlib is deprecated since django 1.8
+"""
+try:
+    import importlib
+except ImportError:
+    from django.utils import importlib

rest_framework/fields.py

@@ -22,11 +22,10 @@
 from django.utils import six, timezone
 from django.utils.encoding import is_protected_type
 from django.utils.translation import ugettext_lazy as _
-from django.utils.datastructures import SortedDict
 from django.utils.dateparse import parse_date, parse_datetime, parse_time
 from rest_framework import ISO_8601
 from rest_framework.compat import (
-    BytesIO, smart_text,
+    BytesIO, smart_text, SortedDict,
     force_text, is_non_str_iterable
 )
 from rest_framework.settings import api_settings

rest_framework/routers.py

@@ -20,8 +20,8 @@
 from django.conf.urls import patterns, url
 from django.core.exceptions import ImproperlyConfigured
 from django.core.urlresolvers import NoReverseMatch
-from django.utils.datastructures import SortedDict
 from rest_framework import views
+from rest_framework.compat import SortedDict
 from rest_framework.response import Response
 from rest_framework.reverse import reverse
 from rest_framework.urlpatterns import format_suffix_patterns

rest_framework/serializers.py

@@ -16,14 +16,13 @@
 import inspect
 import types
 from decimal import Decimal
-from django.contrib.contenttypes.generic import GenericForeignKey
 from django.core.paginator import Page
 from django.db import models
 from django.forms import widgets
 from django.utils import six
-from django.utils.datastructures import SortedDict
 from django.utils.functional import cached_property
 from django.core.exceptions import ObjectDoesNotExist
+from rest_framework.compat import SortedDict, GenericForeignKey
 from rest_framework.settings import api_settings
 
 
@@ -110,9 +109,17 @@ class SortedDictWithMetadata(SortedDict):
     """
     A sorted dict-like object, that can have additional properties attached.
     """
+    def __reduce__(self):
+        """
+        Used by pickle (e.g., caching) if OrderedDict is used instead of SortedDict
+        Overriden to remove the metadata from the dict, since it shouldn't be
+        pickle and may in some instances be unpickleable.
+        """
+        return self.__class__, (SortedDict(self), )
+
     def __getstate__(self):
         """
-        Used by pickle (e.g., caching).
+        Used by pickle (e.g., caching) in SortedDict
         Overriden to remove the metadata from the dict, since it shouldn't be
         pickle and may in some instances be unpickleable.
         """

rest_framework/settings.py

@@ -19,8 +19,9 @@
 """
 from __future__ import unicode_literals
 from django.conf import settings
-from django.utils import importlib, six
+from django.utils import six
 from rest_framework import ISO_8601
+from rest_framework.compat import importlib
 
 
 USER_SETTINGS = getattr(settings, 'REST_FRAMEWORK', None)

rest_framework/utils/encoders.py

@@ -4,9 +4,8 @@
 from __future__ import unicode_literals
 from django.utils import timezone
 from django.db.models.query import QuerySet
-from django.utils.datastructures import SortedDict
 from django.utils.functional import Promise
-from rest_framework.compat import force_text
+from rest_framework.compat import force_text, SortedDict
 from rest_framework.serializers import DictWithMetadata, SortedDictWithMetadata
 import datetime
 import decimal

rest_framework/views.py

@@ -5,10 +5,9 @@
 
 from django.core.exceptions import PermissionDenied
 from django.http import Http404
-from django.utils.datastructures import SortedDict
 from django.views.decorators.csrf import csrf_exempt
 from rest_framework import status, exceptions
-from rest_framework.compat import smart_text, HttpResponseBase, View
+from rest_framework.compat import smart_text, HttpResponseBase, SortedDict, View
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.settings import api_settings

tests/test_fields.py

@@ -10,8 +10,8 @@
 from django.core import validators
 from django.db import models
 from django.test import TestCase
-from django.utils.datastructures import SortedDict
 from rest_framework import serializers
+from rest_framework.compat import SortedDict
 from tests.models import RESTFrameworkModel