MonthMixin.get_previous_month incorrect under certain conditions

[Mark Sundstrom]

In the class-based generic views, MonthMixin.get_previous_month will give an incorrect result when allow_empty is False and there are no records that exist for the first day of the previous month.

For example, consider the Books model in the generic_views regression test cases, with 3 books with the pubdates:

2010-09-01
2010-10-02
2010-11-03

/dates/books/2010/oct/ should return a context where previous_month is 2010-09-01
and
/dates/books/2010/nov/ should similarly return 2010-10-01

However, in the second case, 2010-09-01 is returned instead. This is because the date that is passed to the helper function, _get_next_prev_month, (i.e., naive_result), is 2010-10-01, and the subsequent database lookup is for a record before to that date. Hence, the existing record dated 2010-10-02, is skipped and the previous month is returned instead.

Changing MonthMixin.get_previous_month to instead pass in the last day of the previous month, instead of the first day, fixes this problem.

Test demonstrating the problem and a patch for django.views.generic.dates.py included. (patch fixes 3 typos also)

[Mark Sundstrom]

Patch for dates.py

[Mark Sundstrom]

test case demonstrating the problem

[Mark Sundstrom]

the test case that should go in generic_views/dates.py (I can't get the tests.diff to upload)

[Łukasz Rekucki]

The "tests.diff" actually got uploaded. It's the Trac that sometimes has trouble displaying patches.

[Mark Sundstrom]

Same test and fix as before, but all combined into one diff

[Russell Keith-Magee]

In [15438]:

Fixed #14711 -- Corrected the calculation for the previous month in generic date views. Thanks to msundstr for the report and patch.

[Jacob]

Milestone 1.3 deleted