Ticket #7161: date_based.next_prev.diff

django/views/generic/date_based.py

@@ -107 +107 @@
     Context:
         month:
             (date) this month
+        previous_month:
+            (date) the first day of the previous month containing published objects, or None
         next_month:
-            (date) the first day of the next month, or None if the next month is in the future
-        previous_month:
-            (date) the first day of the previous month
+            (date) the first day of the next month containing published objects, or None
         object_list:
             list of objects published in the given month
     """
@@ -138 +138 @@
     if not object_list and not allow_empty:
         raise Http404
 
-    # 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)
-    else:
-        next_month = None
-
+    # Prepare the DateQuerySet for lazy querying of previous_month / next_month.
+    months_lookup_kwargs = {}
+    if not allow_future:
+        months_lookup_kwargs['%s__lte' % date_field] = now
+    all_months = queryset.filter(**months_lookup_kwargs).dates(date_field, 'month')
+        
+    def previous_month():
+        months = list(all_months)
+        date_index = months.index(datetime.datetime(*date.timetuple()[:3]))
+        # Is this the first month?
+        if date_index == 0:
+            return None
+        else:
+            return months[date_index-1].date()
+ 
+    def next_month():
+        months = list(all_months)
+        date_index = months.index(datetime.datetime(*date.timetuple()[:3]))
+        # Is this the last month?
+        if date_index == len(months) - 1:
+            return None
+        else:
+            return months[date_index+1].date()
+   
     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)
     c = RequestContext(request, {
         '%s_list' % template_object_name: object_list,
         'month': date,
+        'previous_month': previous_month,
         'next_month': next_month,
-        'previous_month': first_day - datetime.timedelta(days=1),
     }, context_processors)
     for key, value in extra_context.items():
         if callable(value):
@@ -225 +241 @@
         day:
             (datetime) the day
         previous_day
-            (datetime) the previous day
+            (datetime) the previous day containing published objects, or None
         next_day
-            (datetime) the next day, or None if the current day is today
+            (datetime) the next day containing published objects, or None
     """
     if extra_context is None: extra_context = {}
     try:
@@ -249 +265 @@
     object_list = queryset.filter(**lookup_kwargs)
     if not allow_empty and not object_list:
         raise Http404
-
-    # Calculate the next day, if applicable.
-    if allow_future:
-        next_day = date + datetime.timedelta(days=1)
-    elif date < datetime.date.today():
-        next_day = date + datetime.timedelta(days=1)
-    else:
-        next_day = None
-
+   
+    # Prepare the DateQuerySet for lazy querying of previous_day / next_day.
+    days_lookup_kwargs = {}
+    if not allow_future:
+        days_lookup_kwargs['%s__lte' % date_field] = now
+    all_days = queryset.filter(**days_lookup_kwargs).dates(date_field, 'day')
+        
+    def previous_day():
+        days = list(all_days)
+        date_index = days.index(datetime.datetime(*date.timetuple()[:3]))
+        # Is this the first day?
+        if date_index == 0:
+            return None
+        else:
+            return days[date_index-1].date()
+ 
+    def next_day():
+        days = list(all_days)
+        date_index = days.index(datetime.datetime(*date.timetuple()[:3]))
+        # Is this the last day?
+        if date_index == len(days) - 1:
+            return None
+        else:
+            return days[date_index+1].date()
+ 
     if not template_name:
         template_name = "%s/%s_archive_day.html" % (model._meta.app_label, model._meta.object_name.lower())
     t = template_loader.get_template(template_name)
     c = RequestContext(request, {
         '%s_list' % template_object_name: object_list,
         'day': date,
-        'previous_day': date - datetime.timedelta(days=1),
+        'previous_day': previous_day,
         'next_day': next_day,
     }, context_processors)
     for key, value in extra_context.items():

docs/generic_views.txt

@@ -396 +396 @@
     * ``month``: A ``datetime.date`` object representing the given month.
 
     * ``next_month``: A ``datetime.date`` object representing the first day of
-      the next month. If the next month is in the future, this will be
-      ``None``.
+      the next month containing published items. If ``month`` is the last month
+      with published items, this will be ``None``.
 
     * ``previous_month``: A ``datetime.date`` object representing the first day
-      of the previous month. Unlike ``next_month``, this will never be
-      ``None``.
+      of the previous month containing published items. If ``month`` is the
+      first month with published items, this will be ``None``.
 
     * ``object_list``: A list of objects available for the given month. This
       variable's name depends on the ``template_object_name`` parameter, which
@@ -561 +561 @@
 
     * ``day``: A ``datetime.date`` object representing the given day.
 
-    * ``next_day``: A ``datetime.date`` object representing the next day. If
-      the next day is in the future, this will be ``None``.
+    * ``next_day``: A ``datetime.date`` object representing the next day
+      containing published items. If ``day`` is the last day with published
+      items, this will be ``None``.
 
-    * ``previous_day``: A ``datetime.date`` object representing the given day.
-      Unlike ``next_day``, this will never be ``None``.
+    * ``previous_day``: A ``datetime.date`` object representing the previous day
+      containing published items. If ``day`` is the first day with published
+      items, this will be ``None``.
 
     * ``object_list``: A list of objects available for the given day. This
       variable's name depends on the ``template_object_name`` parameter, which