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Fix HTMLFormRenderer with empty datetime values #9928

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Merged
browniebroke merged 2 commits into from
Mar 24, 2026
+22 −5
Merged

Fix HTMLFormRenderer with empty datetime values #9928

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fa266dd
Fixed HTMLFormRenderer empty datetime value.
p-r-a-v-i-n Mar 19, 2026
7966d30
Added additional regression coverage
p-r-a-v-i-n Mar 20, 2026
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11 changes: 6 additions & 5 deletions rest_framework/renderers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -345,7 +345,7 @@ def render_field(self, field, parent_style):
except AttributeError:
format_ = api_settings.DATETIME_FORMAT

if format_ is not None:
if format_ is not None and field.value not in (None, ''):
# field.value is expected to be a string
# https://www.django-rest-framework.org/api-guide/fields/#datetimefield
field_value = field.value
Expand All @@ -358,10 +358,11 @@ def render_field(self, field, parent_style):
else datetime.datetime.strptime(field_value, format_)
)
Comment on lines 348 to 359

# The format of an input type="datetime-local" is "yyyy-MM-ddThh:mm"
# followed by optional ":ss" or ":ss.SSS", so keep only the first three
# digits of milliseconds to avoid browser console error.
field.value = field.value.replace(tzinfo=None).isoformat(timespec="milliseconds")
if isinstance(field.value, datetime.datetime):
# The format of an input type="datetime-local" is "yyyy-MM-ddThh:mm"
# followed by optional ":ss" or ":ss.SSS", so keep only the first three
# digits of milliseconds to avoid browser console error.
field.value = field.value.replace(tzinfo=None).isoformat(timespec="milliseconds")

if 'template' in style:
template_name = style['template']
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8 changes: 8 additions & 0 deletions tests/test_renderers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -566,6 +566,14 @@ def test_datetime_field_rendering_timezone_aware_datetime(self):
"2024-12-23T09:55:30.345" # Rendered in -06:00
)

def test_datetime_field_rendering_empty_string_raises_no_error(self):
"""
Regression test for #9927 (issue):
Ensures that an empty string value doesn't cause a ValueError
when the HTMLFormRenderer tries to parse it via fromisoformat.
"""
self._assert_datetime_rendering("", "")


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browniebroke marked this conversation as resolved.
class TestHTMLFormRenderer(TestCase):
def setUp(self):
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