Fixed #2443 -- Added DurationField.

A field for storing periods of time - modeled in Python by timedelta. It
is stored in the native interval data type on PostgreSQL and as a bigint
of microseconds on other backends.

Also includes significant changes to the internals of time related maths
in expressions, including the removal of DateModifierNode.

Thanks to Tim and Josh in particular for reviews.

1 files changed, 17 insertions, 0 deletions

diff --git a/docs/ref/forms/fields.txt b/docs/ref/forms/fields.txt
index 0f13adc249..b63826d9b1 100644
--- a/docs/ref/forms/fields.txt
+++ b/docs/ref/forms/fields.txt
@@ -546,6 +546,23 @@ For each field, we describe the default widget used if you don't specify
 
         The maximum number of decimal places permitted.
 
+``DurationField``
+~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 1.8
+
+.. class:: DurationField(**kwargs)
+
+    * Default widget: :class:`TextInput`
+    * Empty value: ``None``
+    * Normalizes to: A Python :class:`~python:datetime.timedelta`.
+    * Validates that the given value is a string which can be converted into a
+      ``timedelta``.
+    * Error message keys: ``required``, ``invalid``.
+
+    Accepts any format understood by
+    :func:`~django.utils.dateparse.parse_duration`.
+
 ``EmailField``
 ~~~~~~~~~~~~~~