[6.x] Format dates in generated fields in the site’s locale

CHANGELOG-WIP.md

@@ -129,6 +129,7 @@
 - Table columns with invalid settings are now flagged in the Table field’s settings, and link setting validation errors in Link, Markdown, and Table fields now name the setting. ([#19998](https://github.com/craftcms/cms/pull/19998))
 - Added support for configuring field layout field instruction positions.
 - Field layouts with a card view designer now show it and the content tab designer in “Content” and “Appearance” tabs, with Generated Fields in the Content tab. ([#20001](https://github.com/craftcms/cms/pull/20001)), ([#20003](https://github.com/craftcms/cms/pull/20003))
+- Generated fields now show dates in their site’s locale, the way element cards show them, when their template outputs a date directly, such as `{postDate}` or a Date field’s `{startDate}`. Filters still get the date, so `{startDate|date('Y')}` works as before. Generated fields are now also rendered in their site’s language, like entry title formats. ([#20467](https://github.com/craftcms/cms/pull/20467))
 - Entry types’ Icon and Color settings are now in their field layout designer’s Appearance tab, above Card Attributes. ([#20001](https://github.com/craftcms/cms/pull/20001))
 - Card view designers’ previews now reflect the owner’s color, icon, and name, such as an entry type’s, as they’re edited. ([#20001](https://github.com/craftcms/cms/pull/20001))
 - Entry type and user group descriptions, fields’ default instructions, tips, and warnings, and field layout elements’ instructions, tips, and warnings now have Markdown inputs. ([#20001](https://github.com/craftcms/cms/pull/20001))

CHANGELOG.md

@@ -364,6 +364,7 @@
 - Entry types’ Icon and Color settings are now in their field layout designer’s Appearance tab, above Card Attributes. ([#20001](https://github.com/craftcms/cms/pull/20001))
 - Card view designers’ previews now include a sample chip above the card, which reflects the owner’s color and whether its cards have thumbnails. ([#20003](https://github.com/craftcms/cms/pull/20003))
 - Field layouts’ Generated Fields setting is now in the field layout designer’s Content tab. ([#20003](https://github.com/craftcms/cms/pull/20003))
+- Generated fields now show dates in their site’s locale, the way element cards show them, when their template outputs a date directly, such as `{postDate}` or a Date field’s `{startDate}`. Filters still get the date, so `{startDate|date('Y')}` works as before. Generated fields are now also rendered in their site’s language, like entry title formats. Existing values update the next time their elements are saved, such as with `php artisan craft:resave:all`. ([#20467](https://github.com/craftcms/cms/pull/20467))
 - Field layout element and dashboard widget width pickers now preview the new width on hover. ([#20001](https://github.com/craftcms/cms/pull/20001))
 - Added `CraftCms\Cms\FieldLayout\FieldLayout::getCardThumbStyle()`, `setCardThumbStyle()`, and `cardThumbStyle()`, and the `cardThumbStyle` field layout config key. ([#20148](https://github.com/craftcms/cms/pull/20148))
 - Added `CraftCms\Cms\FieldLayout\FieldLayout::$thumbSources` and `thumbSources()`, and the `thumbSources` field layout config key, which replaces `thumbFieldKey`. ([#20156](https://github.com/craftcms/cms/discussions/20156), [#20181](https://github.com/craftcms/cms/pull/20181))

src/Element/Operations/ElementWrites.php

@@ -4,6 +4,7 @@
 
 namespace CraftCms\Cms\Element\Operations;
 
+use Carbon\CarbonInterface;
 use CraftCms\Cms\Database\Table;
 use CraftCms\Cms\Element\Contracts\ElementInterface;
 use CraftCms\Cms\Element\Contracts\NestedElementInterface;
@@ -32,6 +33,7 @@
 use CraftCms\Cms\Element\Queries\Exceptions\ElementNotFoundException;
 use CraftCms\Cms\Element\Queries\Exceptions\QueryAbortedException;
 use CraftCms\Cms\Element\Validation\ElementRules;
+use CraftCms\Cms\Field\Contracts\PreviewableFieldInterface;
 use CraftCms\Cms\Field\MissingField;
 use CraftCms\Cms\FieldLayout\FieldLayout;
 use CraftCms\Cms\Search\Search;
@@ -40,14 +42,19 @@
 use CraftCms\Cms\Support\Arr;
 use CraftCms\Cms\Support\DateTimeHelper;
 use CraftCms\Cms\Support\Facades\BulkOps;
+use CraftCms\Cms\Support\Facades\I18N;
 use CraftCms\Cms\Support\Html;
 use CraftCms\Cms\Support\Json;
 use CraftCms\Cms\Support\Query;
 use CraftCms\Cms\Support\Str;
+use CraftCms\Cms\Support\Typecast;
 use CraftCms\Cms\Support\Url;
+use CraftCms\Cms\Translation\Locale;
+use DateTimeInterface;
 use Exception;
 use Illuminate\Container\Attributes\Singleton;
 use Illuminate\Database\Query\Builder;
+use Illuminate\Support\Facades\Date;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Log;
 use Throwable;
@@ -115,9 +122,16 @@ public function completeGeneratedFields(ElementInterface $element): void
             }
             $generatedFieldValues = [];
             $updated = false;
+            $language = $siteElement->getSite()->getLanguage();
 
             foreach ($generatedFields as $field) {
-                $value = renderObjectTemplate($field['template'] ?? '', $siteElement, escaperStrategy: 'html');
+                $template = $field['template'] ?? '';
+                $value = I18N::withLocale($language, $language, fn () => renderObjectTemplate(
+                    $template,
+                    $siteElement,
+                    $this->generatedFieldDateVariables($siteElement, $template),
+                    escaperStrategy: 'html',
+                ));
                 $value = normalizeValue($value) ?? '';
 
                 if ($value !== ($content[$field['uid']] ?? '')) {
@@ -141,6 +155,48 @@ public function completeGeneratedFields(ElementInterface $element): void
         }
     }
 
+    /**
+     * Returns the date values that a generated field template references, set to print
+     * in the current locale the way element cards show them.
+     *
+     * Passed as object template variables, they take precedence over the element’s own
+     * values for `{foo}` shorthand, while filters like `|date` still get a date.
+     *
+     * @return array<string, CarbonInterface>
+     */
+    private function generatedFieldDateVariables(ElementInterface $element, string $template): array
+    {
+        $variables = [];
+        $isReferenced = fn (string $name): bool => (bool) preg_match(sprintf('/\b%s\b/', preg_quote($name, '/')), $template);
+        $formatDatetime = fn (DateTimeInterface $date): string => I18N::getFormatter()->asDatetime($date, Locale::LENGTH_SHORT);
+
+        foreach ($element->attributes() as $attribute) {
+            if (
+                $isReferenced($attribute) &&
+                Typecast::isDateTimeProperty($element::class, $attribute) &&
+                ($value = $element->$attribute ?? null) instanceof DateTimeInterface
+            ) {
+                $variables[$attribute] = Date::instance($value)->settings(['toStringFormat' => $formatDatetime]);
+            }
+        }
+
+        foreach ($element->getFieldLayout()?->getCustomFields() ?? [] as $field) {
+            if (
+                ! isset($variables[$field->handle]) &&
+                $isReferenced($field->handle) &&
+                ($value = $element->getFieldValue($field->handle)) instanceof DateTimeInterface
+            ) {
+                $variables[$field->handle] = Date::instance($value)->settings([
+                    'toStringFormat' => $field instanceof PreviewableFieldInterface
+                        ? fn (DateTimeInterface $date): string => $field->getPreviewHtml($date, $element)
+                        : $formatDatetime,
+                ]);
+            }
+        }
+
+        return $variables;
+    }
+
     public function saveElement(
         ElementInterface $element,
         bool $runValidation = true,

tests/Feature/Element/ElementWrites/SaveElementTest.php

@@ -20,6 +20,7 @@
 use CraftCms\Cms\Entry\Elements\Entry;
 use CraftCms\Cms\Entry\Models\Entry as EntryModel;
 use CraftCms\Cms\Entry\Models\EntryType;
+use CraftCms\Cms\Field\Date;
 use CraftCms\Cms\Field\Matrix;
 use CraftCms\Cms\Field\Models\Field;
 use CraftCms\Cms\Field\PlainText;
@@ -500,6 +501,27 @@ function createEntryWithPlainTextField(array $entryAttributes = []): array
         ->and(count(Event::getListeners(ElementLifecyclePropagated::class)))->toBe($listeners + 1);
 });
 
+it('formats dates that generated fields print in the site’s locale', function () {
+    Sites::getPrimarySite()->setLanguage('de');
+    $entry = EntryModel::factory()
+        ->withField('startDate', Date::class, ['showTime' => true])
+        ->withField('day', Date::class, ['showTime' => false])
+        ->withField('endDate', Date::class)
+        ->createElementWithFields()->element;
+    $entry->getFieldLayout()->setGeneratedFields([[
+        'uid' => 'generated',
+        'handle' => 'dates',
+        'template' => '{startDate} | {day} | {postDate} | {startDate|date("Y")} | [{endDate}]',
+    ]]);
+    $entry->postDate = new DateTime('2026-03-04 05:06:00');
+    $entry->setFieldValue('startDate', new DateTime('2026-10-09 10:00:00'));
+    $entry->setFieldValue('day', new DateTime('2027-02-28'));
+
+    expect($this->writes->saveElement($entry, updateSearchIndex: false))->toBeTrue()
+        ->and($entry->getGeneratedFieldValues()['dates'])
+        ->toBe('09.10.2026, 10:00 PDT | 28.02.2027 | 04.03.2026, 05:06 | 2026 | []');
+});
+
 it('completes nested generated values across localized saves, duplicates, and merges', function () {
     $secondary = Site::factory()->create();
     Sites::refreshSites();