Fixed #10458 -- Corrected the `next_month` and `previous_month` context…

Fixed #10458 -- Corrected the `next_month` and `previous_month` context variables provided with the generic month_archive view. The value returned now matches the docstring and the generic views documentation. Thanks to fperetti for the report and initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10556 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/views/generic/date_based.py

@@ -144,12 +144,18 @@ def archive_month(request, year, month, queryset, date_field,
 
     # Calculate the next month, if applicable.
     if allow_future:
-        next_month = last_day + datetime.timedelta(days=1)
-    elif last_day < datetime.date.today():
-        next_month = last_day + datetime.timedelta(days=1)
+        next_month = last_day
+    elif last_day <= datetime.date.today():
+        next_month = last_day
     else:
         next_month = None
 
+    # Calculate the previous month
+    if first_day.month == 1:
+        previous_month = first_day.replace(year=first_day.year-1,month=12)
+    else:
+        previous_month = first_day.replace(month=first_day.month-1)
+
     if not template_name:
         template_name = "%s/%s_archive_month.html" % (model._meta.app_label, model._meta.object_name.lower())
     t = template_loader.get_template(template_name)
@@ -157,7 +163,7 @@ def archive_month(request, year, month, queryset, date_field,
         '%s_list' % template_object_name: object_list,
         'month': date,
         'next_month': next_month,
-        'previous_month': first_day - datetime.timedelta(days=1),
+        'previous_month': previous_month,
     }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
@@ -239,7 +245,7 @@ def archive_day(request, year, month, day, queryset, date_field,
     """
     if extra_context is None: extra_context = {}
     try:
-        tt = time.strptime('%s-%s-%s' % (year, month, day), 
+        tt = time.strptime('%s-%s-%s' % (year, month, day),
                            '%s-%s-%s' % ('%Y', month_format, day_format))
         date = datetime.date(*tt[:3])
     except ValueError:
@@ -311,7 +317,7 @@ def object_detail(request, year, month, day, queryset, date_field,
     """
     if extra_context is None: extra_context = {}
     try:
-        tt = time.strptime('%s-%s-%s' % (year, month, day), 
+        tt = time.strptime('%s-%s-%s' % (year, month, day),
                            '%s-%s-%s' % ('%Y', month_format, day_format))
         date = datetime.date(*tt[:3])
     except ValueError:

tests/regressiontests/views/tests/generic/date_based.py

 # coding: utf-8
 from django.test import TestCase
-from datetime import datetime
+from datetime import datetime, date
 from datetime import timedelta
 from regressiontests.views.models import Article, Author, DateArticle
 
@@ -52,6 +52,8 @@ class MonthArchiveTest(TestCase):
         article.save()
         response = self.client.get('/views/date_based/archive_month/2004/02/')
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next_month'], date(2004, 3, 1))
+        self.assertEqual(response.context['previous_month'], date(2004, 1, 1))
 
         article.date_created = first_second_of_feb-two_seconds
         article.save()
@@ -62,6 +64,8 @@ class MonthArchiveTest(TestCase):
         article.save()
         response = self.client.get('/views/date_based/archive_month/2004/02/')
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next_month'], date(2004, 3, 1))
+        self.assertEqual(response.context['previous_month'], date(2004, 1, 1))
 
         article.date_created = first_second_of_mar
         article.save()
@@ -74,6 +78,8 @@ class MonthArchiveTest(TestCase):
         article2.save()
         response = self.client.get('/views/date_based/datefield/archive_month/2004/02/')
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next_month'], date(2004, 3, 1))
+        self.assertEqual(response.context['previous_month'], date(2004, 1, 1))
 
         article2.date_created = (first_second_of_feb-two_seconds).date()
         article2.save()
@@ -84,12 +90,27 @@ class MonthArchiveTest(TestCase):
         article2.save()
         response = self.client.get('/views/date_based/datefield/archive_month/2004/02/')
         self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next_month'], date(2004, 3, 1))
+        self.assertEqual(response.context['previous_month'], date(2004, 1, 1))
 
         article2.date_created = first_second_of_mar.date()
         article2.save()
         response = self.client.get('/views/date_based/datefield/archive_month/2004/02/')
         self.assertEqual(response.status_code, 404)
 
+        now = datetime.now()
+        prev_month = now.date().replace(day=1)
+        if prev_month.month == 11:
+            prev_month = prev_month.replace(year=prev_month.year-1, month=12)
+        else:
+            prev_month = prev_month.replace(month=prev_month.month-1)
+        article2.date_created = now
+        article2.save()
+        response = self.client.get('/views/date_based/datefield/archive_month/%s/' % now.strftime('%Y/%m'))
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['next_month'], None)
+        self.assertEqual(response.context['previous_month'], prev_month)
+
 class DayArchiveTests(TestCase):
 
     def test_year_month_day_format(self):