Fixed #11385 -- Made forms.DateTimeField accept ISO 8601 date inputs.

Thanks José Padilla for the initial patch, and Carlton Gibson for the
review.

docs/ref/forms/fields.txt

@@ -490,7 +490,19 @@ For each field, we describe the default widget used if you don't specify
     .. attribute:: input_formats
 
         A list of formats used to attempt to convert a string to a valid
-        ``datetime.datetime`` object.
+        ``datetime.datetime`` object, in addition to ISO 8601 formats.
+
+    The field always accepts strings in ISO 8601 formatted dates or similar
+    recognized by :func:`~django.utils.dateparse.parse_datetime`. Some examples
+    are::
+
+        * '2006-10-25 14:30:59'
+        * '2006-10-25T14:30:59'
+        * '2006-10-25 14:30'
+        * '2006-10-25T14:30'
+        * '2006-10-25T14:30Z'
+        * '2006-10-25T14:30+02:00'
+        * '2006-10-25'
 
     If no ``input_formats`` argument is provided, the default input formats are
     taken from :setting:`DATETIME_INPUT_FORMATS` if :setting:`USE_L10N` is
@@ -498,6 +510,11 @@ For each field, we describe the default widget used if you don't specify
     if localization is enabled. See also :doc:`format localization
     </topics/i18n/formatting>`.
 
+    .. versionchanged:: 3.1
+
+        Support for ISO 8601 date string parsing (including optional timezone)
+        was added.
+
 ``DecimalField``
 ----------------
 

docs/releases/3.1.txt

@@ -179,6 +179,10 @@ Forms
   to access model instances. See :ref:`iterating-relationship-choices` for
   details.
 
+* :class:`django.forms.DateTimeField` now accepts dates in a subset of ISO 8601
+  datetime formats, including optional timezone (e.g. ``2019-10-10T06:47``,
+  ``2019-10-10T06:47:23+04:00``, or ``2019-10-10T06:47:23Z``).
+
 Generic Views
 ~~~~~~~~~~~~~