fix(Import): DateTime import fixes

- do not try to pass `null` to DateTimeImmutable as it would cause an
  Exception
- be stricter on small letter-only values that might be turned into a
  DateTimeImmutable object because they match with timezone abbreviations
- do not consider pure numbers a date

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

lib/Service/ImportService.php

@@ -31,6 +31,9 @@
 use Psr\Container\ContainerExceptionInterface;
 use Psr\Container\NotFoundExceptionInterface;
 use Psr\Log\LoggerInterface;
+use function is_string;
+use function mb_strlen;
+use function preg_match;
 
 class ImportService extends SuperService {
 
@@ -168,12 +171,7 @@ private function getPreviewData(Worksheet $worksheet): array {
 					} else {
 						$format = 'Y-m-d H:i';
 					}
-
-					try {
-						$value = Date::excelToDateTimeObject($value)->format($format);
-					} catch (\TypeError) {
-						$value = (new \DateTimeImmutable($value))->format($format);
-					}
+					$value = $this->parseAndFormatDateTimeString($value, $format);
 				} elseif (($column && $column->getType() === 'number' && $column->getNumberSuffix() === '%')
 					|| (is_array($columns[$colIndex]) && $columns[$colIndex]['type'] === 'number' && $columns[$colIndex]['numberSuffix'] === '%')) {
 					$value = $value * 100;
@@ -382,30 +380,14 @@ private function createRow(Row $row): void {
 				$hasData = $hasData || !empty($value);
 
 				if ($column->getType() === 'datetime') {
-					if ($column->getType() === 'datetime' && $column->getSubtype() === 'date') {
+					if ($column->getSubtype() === 'date') {
 						$format = 'Y-m-d';
-					} elseif ($column->getType() === 'datetime' && $column->getSubtype() === 'time') {
+					} elseif ($column->getSubtype() === 'time') {
 						$format = 'H:i';
 					} else {
 						$format = 'Y-m-d H:i';
 					}
-					try {
-						$value = Date::excelToDateTimeObject($value)->format($format);
-					} catch (\TypeError) {
-						$value = (new \DateTimeImmutable($value))->format($format);
-					}
-				} elseif ($column->getType() === 'datetime' && $column->getSubtype() === 'date') {
-					try {
-						$value = Date::excelToDateTimeObject($value)->format('Y-m-d');
-					} catch (\TypeError) {
-						$value = (new \DateTimeImmutable($value))->format('Y-m-d');
-					}
-				} elseif ($column->getType() === 'datetime' && $column->getSubtype() === 'time') {
-					try {
-						$value = Date::excelToDateTimeObject($value)->format('H:i');
-					} catch (\TypeError) {
-						$value = (new \DateTimeImmutable($value))->format('H:i');
-					}
+					$value = $this->parseAndFormatDateTimeString($value, $format);
 				} elseif ($column->getType() === 'number' && $column->getNumberSuffix() === '%') {
 					$value = $value * 100;
 				} elseif ($column->getType() === 'selection' && $column->getSubtype() === 'check') {
@@ -440,6 +422,37 @@ private function createRow(Row $row): void {
 
 	}
 
+	private function valueToDateTimeImmutable(mixed $value): ?\DateTimeImmutable {
+		if (
+			$value === false
+			|| $value === null
+			|| (is_string($value)
+				&& mb_strlen($value) < 3 // Let pass potential 3-letter month names
+				&& preg_match('/\d/', $value) !== 1) // or anything containing a digit
+		) {
+			return null;
+		}
+		try {
+			$dt = Date::excelToDateTimeObject($value);
+			return \DateTimeImmutable::createFromMutable($dt);
+		} catch (\TypeError) {
+			try {
+				return (new \DateTimeImmutable($value));
+			} catch (\Exception $e) {
+				$this->logger->debug('Could not parse string {value} as date time.', [
+					'exception' => $e,
+					'value' => $value,
+				]);
+				return null;
+			}
+		}
+	}
+
+	private function parseAndFormatDateTimeString(?string $value, string $format): string {
+		$dateTime = $this->valueToDateTimeImmutable($value);
+		return $dateTime?->format($format) ?: '';
+	}
+
 	/**
 	 * @param Row $firstRow
 	 * @param Row $secondRow
@@ -528,17 +541,11 @@ private function parseColumnDataType(Cell $cell): array {
 			'subtype' => 'line',
 		];
 
-		try {
-			if ($value === false) {
-				throw new \Exception('We do not accept `false` here');
-			}
-			$dateValue = new \DateTimeImmutable($value);
-		} catch (\Exception) {
-		}
-
-		if (isset($dateValue)
+		if (!is_numeric($formattedValue)
+			&& ($this->valueToDateTimeImmutable($value) instanceof \DateTimeImmutable
 			|| Date::isDateTime($cell)
-			|| $originDataType === DataType::TYPE_ISO_DATE) {
+			|| $originDataType === DataType::TYPE_ISO_DATE)
+		) {
 			// the formatted value stems from the office document and shows the original user intent
 			$dateAnalysis = date_parse($formattedValue);
 			$containsDate = $dateAnalysis['year'] !== false || $dateAnalysis['month'] !== false || $dateAnalysis['day'] !== false;

tests/integration/features/APIv1.feature

@@ -218,6 +218,32 @@ Feature: APIv1
     | import-from-ms365.xlsx       |
     | import-from-libreoffice.csv  |
 
+  @api1 @import @current
+  Scenario: Import a document with optional field
+    Given user "participant1" uploads file "import-from-libreoffice-optional-fields.csv"
+    And table "Import test" with emoji "👨🏻‍💻" exists for user "participant1" as "base1"
+    When user imports file "/import-from-libreoffice-optional-fields.csv" into last created table
+    Then import results have the following data
+      | found_columns_count     |  9 |
+      | created_columns_count   |  9 |
+      | inserted_rows_count     |  2 |
+      | errors_count            |  0 |
+    # At the moment, we only take the first row into account, when determining the cell format
+    # Hence, it is expected that all turn out to be text
+    Then table has at least following typed columns
+      | Case    | text      |
+      | Col1    | text      |
+      | num     | text    |
+      | emoji   | text      |
+      | special | text      |
+      | date    | text  |
+      | truth   | text |
+    # the library handles "true" as boolean and so is converted into the text representation "1"
+    Then table contains at least following rows
+      | Case | Date and Time    | Col1    | num   | emoji | special  | date       | truth | time  |
+      | A    | | | | | | | | |
+      | B    | 2016-06-01 13:37 | great   |  99    | ⚠     | Ö        | 2016-06-01 | 1     | 01:23 |
+
   @api1
   Scenario: Create, edit and delete views
     Given table "View test" with emoji "👨🏻‍💻" exists for user "participant1" as "view-test"

tests/integration/resources/import-from-libreoffice-optional-fields.csv

@@ -0,0 +1,3 @@
+Case,Date and Time,Col1,num,emoji,special,date,truth,time
+A,,,,,,,,
+B,2016-06-01 13:37,great,99,⚠,Ö,2016-06-01,true,01:23

tests/integration/resources/import-from-libreoffice-optional-fields.csv.license

@@ -0,0 +1,2 @@
+SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+SPDX-License-Identifier: AGPL-3.0-or-later