get_next_by_pub_date/get_previous_by_pub_date model methods only see 1 item for each day.

[mattycakes@…]

The model.get_next_by_pub_date() and model.get_previous_by_pub_date() methods appear to only see one item for each day.

For example, I have a blog.posts model in which pub_date is a DateTimeField. If there are multiple posts in one day, the above methods will only see the first post for each day, and then skip to the next day. This is clearly wrong behaviour; the method should retrieve the next item by date whether it was created the same day or not.

Example:

item1.pub_date = 2005/01/01 12:00
item2.pub_date = 2005/01/02 8:00
item3.pub_date = 2005/01/02 9:00

item1.get_next… = item2
item2.get_next… = None
item3.get_prev… = item1

[mattycakes@…]

In fact, it only has this problem if multiple items have the same time as well as the same date.

Example:

item1.pub_date = 2005/01/01 12:00
item2.pub_date = 2005/01/02 8:07
item3.pub_date = 2005/01/02 8:07

item1.get_next… = item2
item2.get_next… = None
item3.get_prev… = item1

The above is valid; my first example, however, is wrong.

[Adrian Holovaty]

In [1152] I added some unit tests for this. I can't recreate the problem -- the tests run fine. Please reopen with more information on how to recreate the bug.

[mattycakes@…]

I've added a few tests. Hopefully these help clarify the problem.

Index: tests/testapp/models/lookup.py
===================================================================
--- tests/testapp/models/lookup.py	(revision 1154)
+++ tests/testapp/models/lookup.py	(working copy)
@@ -103,4 +103,16 @@
 Article 4
 >>> a5.get_previous_by_pub_date()
 Article 6
+>>> a4.get_previous_by_pub_date()
+Article 3
+>>> a3.get_previous_by_pub_date()
+Article 2
+>>> a2.get_previous_by_pub_date()
+Article 1
+>>> a1.get_next_by_pub_date()
+Article 2
+>>> a2.get_next_by_pub_date()
+Article 3
+>>> a3.get_next_by_pub_date()
+Article 4
 """

[mattycakes@…]

Patch to lookup API tests

[Adrian Holovaty]

(In [1155]) Fixed #724 -- Ensured get_next_by_FOO() and get_previous_by_FOO() methods don't skip or duplicate any records in the case of duplicate values. Thanks for reporting the bug, mattycakes@…