Fixed #5363 -- HTML5 datetime-local valid format HTMLFormRenderer

rest_framework/renderers.py

@@ -10,6 +10,7 @@
 import base64
 import contextlib
 import datetime
+import sys
 from urllib import parse
 
 from django import forms
@@ -22,7 +23,7 @@
 from django.utils.http import parse_header_parameters
 from django.utils.safestring import SafeString
 
-from rest_framework import VERSION, exceptions, serializers, status
+from rest_framework import ISO_8601, VERSION, exceptions, serializers, status
 from rest_framework.compat import (
     INDENT_SEPARATORS, LONG_SEPARATORS, SHORT_SEPARATORS, coreapi, coreschema,
     pygments_css, yaml
@@ -339,11 +340,32 @@ def render_field(self, field, parent_style):
             style['template_pack'] = parent_style.get('template_pack', self.template_pack)
         style['renderer'] = self
 
-        # Get a clone of the field with text-only value representation.
+        # Get a clone of the field with text-only value representation ('' if None or False).
         field = field.as_form_field()
 
-        if style.get('input_type') == 'datetime-local' and isinstance(field.value, str):
-            field.value = field.value.rstrip('Z')
+        if style.get('input_type') == 'datetime-local':
+            try:
+                format_ = field._field.format
+            except AttributeError:
+                format_ = api_settings.DATETIME_FORMAT
+
+            if format_ is not None:
+                # field.value is expected to be a string
+                # https://www.django-rest-framework.org/api-guide/fields/#datetimefield
+                field_value = field.value
+                if format_ == ISO_8601 and sys.version_info < (3, 11):
+                    # We can drop this branch once we drop support for Python < 3.11
+                    # https://docs.python.org/3/whatsnew/3.11.html#datetime
+                    field_value = field_value.rstrip('Z')
+                field.value = (
+                    datetime.datetime.fromisoformat(field_value) if format_ == ISO_8601
+                    else datetime.datetime.strptime(field_value, format_)
+                )
+
+            # 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']

tests/test_renderers.py

@@ -1,5 +1,7 @@
 import re
 from collections.abc import MutableMapping
+from datetime import datetime
+from zoneinfo import ZoneInfo
 
 import pytest
 from django.core.cache import cache
@@ -488,6 +490,85 @@ class TestSerializer(serializers.Serializer):
         assert rendered == ''
 
 
+class TestDateTimeFieldHTMLFormRender(TestCase):
+    """
+    Default USE_TZ is True.
+    Default TIME_ZONE is 'America/Chicago'.
+    """
+
+    def _assert_datetime_rendering(self, appointment, expected, datetimefield_kwargs=None):
+        datetimefield_kwargs = datetimefield_kwargs or {}
+
+        class TestSerializer(serializers.Serializer):
+            appointment = serializers.DateTimeField(**datetimefield_kwargs)
+
+        serializer = TestSerializer(data={"appointment": appointment})
+        serializer.is_valid()
+        renderer = HTMLFormRenderer()
+        field = serializer['appointment']
+        rendered = renderer.render_field(field, {})
+        expected_html = (
+            '<input name="appointment" class="form-control" '
+            f'type="datetime-local" value="{expected}">'
+        )
+
+        self.assertInHTML(expected_html, rendered)
+
+    def test_datetime_field_rendering_milliseconds(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678), "2024-12-24T00:55:30.345"
+        )
+
+    def test_datetime_field_rendering_no_seconds_and_no_milliseconds(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 0, 0), "2024-12-24T00:55:00.000"
+        )
+
+    def test_datetime_field_rendering_with_format_as_none(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678),
+            "2024-12-24T00:55:30.345",
+            {"format": None}
+        )
+
+    def test_datetime_field_rendering_with_format(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678),
+            "2024-12-24T00:55:00.000",
+            {"format": "%a %d %b %Y, %I:%M%p"}
+        )
+
+    # New project templates default to 'UTC'.
+    @override_settings(TIME_ZONE='UTC')
+    def test_datetime_field_rendering_utc(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678),
+            "2024-12-24T00:55:30.345"
+        )
+
+    @override_settings(REST_FRAMEWORK={'DATETIME_FORMAT': '%a %d %b %Y, %I:%M%p'})
+    def test_datetime_field_rendering_with_custom_datetime_format(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678),
+            "2024-12-24T00:55:00.000"
+        )
+
+    @override_settings(REST_FRAMEWORK={'DATETIME_FORMAT': None})
+    def test_datetime_field_rendering_datetime_format_is_none(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678),
+            "2024-12-24T00:55:30.345"
+        )
+
+    # Enforce it in True because in Django versions under 4.2 was False by default.
+    @override_settings(USE_TZ=True)
+    def test_datetime_field_rendering_timezone_aware_datetime(self):
+        self._assert_datetime_rendering(
+            datetime(2024, 12, 24, 0, 55, 30, 345678, tzinfo=ZoneInfo('Asia/Tokyo')),  # +09:00
+            "2024-12-23T09:55:30.345"  # Rendered in -06:00
+        )
+
+
 class TestHTMLFormRenderer(TestCase):
     def setUp(self):
         class TestSerializer(serializers.Serializer):