[1.7.x] Fixed #22502 -- Fixed microseconds/default/form interaction

Made explicit lack of microsecond handling by built-in datetime form
fields. Used that explicitness to appropriately nix microsecond
values in bound fields. Thanks Claude Paroz for the review.
Backport of a5de0df58 from master.

1 files changed, 6 insertions, 0 deletions

diff --git a/django/forms/forms.py b/django/forms/forms.py
index 5362fd5aaf..2cfd4ec241 100644
--- a/django/forms/forms.py
+++ b/django/forms/forms.py
@@ -6,6 +6,7 @@ from __future__ import unicode_literals
 
 from collections import OrderedDict
 import copy
+import datetime
 import warnings
 
 from django.core.exceptions import ValidationError, NON_FIELD_ERRORS
@@ -590,6 +591,11 @@ class BoundField(object):
             data = self.form.initial.get(self.name, self.field.initial)
             if callable(data):
                 data = data()
+                # If this is an auto-generated default date, nix the
+                # microseconds for standardized handling. See #22502.
+                if (isinstance(data, (datetime.datetime, datetime.time)) and
+                        not getattr(self.field.widget, 'supports_microseconds', True)):
+                    data = data.replace(microsecond=0)
         else:
             data = self.field.bound_data(
                 self.data, self.form.initial.get(self.name, self.field.initial)