Use '.callback' property instead of private attributes when inspectin…

…g urlpatterns

rest_framework/compat.py

@@ -60,17 +60,21 @@ def distinct(queryset, base):
 
 def get_names_and_managers(options):
     if django.VERSION >= (1, 10):
+        # Django 1.10 onwards provides a `.managers` property on the Options.
         return [
             (manager.name, manager)
             for manager
             in options.managers
         ]
+    # For Django 1.8 and 1.9, use the three-tuple information provided
+    # by .concrete_managers and .abstract_managers
     return [
         (manager_info[1], manager_info[2])
         for manager_info
         in (options.concrete_managers + options.abstract_managers)
     ]
 
+
 # contrib.postgres only supported from 1.8 onwards.
 try:
     from django.contrib.postgres import fields as postgres_fields

rest_framework/urlpatterns.py

@@ -24,7 +24,7 @@ def apply_suffix_patterns(urlpatterns, suffix_pattern, suffix_required):
         else:
             # Regular URL pattern
             regex = urlpattern.regex.pattern.rstrip('$').rstrip('/') + suffix_pattern
-            view = urlpattern._callback or urlpattern._callback_str
+            view = urlpattern.callback
             kwargs = urlpattern.default_args
             name = urlpattern.name
             # Add in both the existing and the new urlpattern