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authorChad Shryock <chad@isl.co>2016-06-02 10:52:58 -0700
committerTim Graham <timograham@gmail.com>2016-06-02 19:42:08 -0400
commite6c5e68acd4bff90e371fd148ed6976e147692ad (patch)
treeac8c516d30e3af590327fde79e5dbe380ee9f285 /docs/ref
parentc7b1b81352533be9b7f4637c12219f59c0964a82 (diff)
Fixed #26526 -- Documented QuerySet.latest()'s dependency on database ordering.
Diffstat (limited to 'docs/ref')
-rw-r--r--docs/ref/models/querysets.txt11
1 files changed, 11 insertions, 0 deletions
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index e8753971c3..34ec26466c 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -1952,6 +1952,17 @@ given parameters.
Note that ``earliest()`` and ``latest()`` exist purely for convenience and
readability.
+.. admonition:: ``earliest()`` and ``latest()`` may return instances with null dates.
+
+ Since ordering is delegated to the database, results on fields that allow
+ null values may be ordered differently if you use different databases. For
+ example, PostgreSQL and MySQL sort null values as if they are higher than
+ non-null values, while SQLite does the opposite.
+
+ You may want to filter out null values::
+
+ Entry.objects.filter(pub_date__isnull=False).latest('pub_date')
+
``earliest()``
~~~~~~~~~~~~~~