switch to using format strings in error messages; raise NotFound when pagination fails to provide a more useful error message

2 files changed, 22 insertions, 20 deletions

diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index c8cedfce..dfc57293 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -7,8 +7,7 @@ In addition Django's built in 403 and 404 exceptions are handled.
 from __future__ import unicode_literals
 from django.utils import six
 from django.utils.encoding import force_text
-from django.utils.translation import ugettext_lazy as _
-from django.utils.translation import ungettext_lazy
+from django.utils.translation import ugettext_lazy as _, ungettext
 from rest_framework import status
 import math
 
@@ -96,13 +95,13 @@ class NotFound(APIException):
 
 class MethodNotAllowed(APIException):
     status_code = status.HTTP_405_METHOD_NOT_ALLOWED
-    default_detail = _("Method '%s' not allowed.")
+    default_detail = _("Method {method} not allowed.")
 
     def __init__(self, method, detail=None):
         if detail is not None:
             self.detail = force_text(detail)
         else:
-            self.detail = force_text(self.default_detail) % method
+            self.detail = force_text(self.default_detail).format(method=method)
 
 
 class NotAcceptable(APIException):
@@ -119,23 +118,22 @@ class NotAcceptable(APIException):
 
 class UnsupportedMediaType(APIException):
     status_code = status.HTTP_415_UNSUPPORTED_MEDIA_TYPE
-    default_detail = _("Unsupported media type '%s' in request.")
+    default_detail = _("Unsupported media type '{media_type}' in request.")
 
     def __init__(self, media_type, detail=None):
         if detail is not None:
             self.detail = force_text(detail)
         else:
-            self.detail = force_text(self.default_detail) % media_type
+            self.detail = force_text(self.default_detail).format(
+                media_type=media_type
+            )
 
 
 class Throttled(APIException):
     status_code = status.HTTP_429_TOO_MANY_REQUESTS
     default_detail = _('Request was throttled.')
-    extra_detail = ungettext_lazy(
-        'Expected available in %(wait)d second.',
-        'Expected available in %(wait)d seconds.',
-        'wait'
-    )
+    extra_detail_singular = 'Expected available in {wait} second.'
+    extra_detail_plural = 'Expected available in {wait} seconds.'
 
     def __init__(self, wait=None, detail=None):
         if detail is not None:
@@ -147,6 +145,8 @@ class Throttled(APIException):
             self.wait = None
         else:
             self.wait = math.ceil(wait)
-            self.detail += ' ' + force_text(
-                self.extra_detail % {'wait': self.wait}
-            )
+            self.detail += ' ' + force_text(ungettext(
+                self.extra_detail_singular.format(wait=self.wait),
+                self.extra_detail_plural.format(wait=self.wait),
+                self.wait
+            ))
diff --git a/rest_framework/generics.py b/rest_framework/generics.py
index 680992d7..fe92355d 100644
--- a/rest_framework/generics.py
+++ b/rest_framework/generics.py
@@ -10,6 +10,7 @@ from django.shortcuts import get_object_or_404 as _get_object_or_404
 from django.utils import six
 from django.utils.translation import ugettext as _
 from rest_framework import views, mixins
+from rest_framework.exceptions import NotFound
 from rest_framework.settings import api_settings
 
 
@@ -119,15 +120,16 @@ class GenericAPIView(views.APIView):
             if page == 'last':
                 page_number = paginator.num_pages
             else:
-                raise Http404(_("Choose a valid page number. Page numbers must be a whole number, or must be the string 'last'."))
+                raise NotFound(_("Choose a valid page number. Page numbers must be a whole number, or must be the string 'last'."))
+
+        page_number = -1
         try:
             page = paginator.page(page_number)
         except InvalidPage as exc:
-            error_format = _('Invalid page (%(page_number)s): %(message)s')
-            raise Http404(error_format % {
-                'page_number': page_number,
-                'message': six.text_type(exc)
-            })
+            error_format = _('Invalid page ({page_number}): {message}')
+            raise NotFound(error_format.format(
+                page_number=page_number, message=six.text_type(exc)
+            ))
 
         return page