From 808546a89aaa5eee7e5662705eefe15a8f84db85 Mon Sep 17 00:00:00 2001
From: Kostiantyn Miakshyn <molodchick@gmail.com>
Date: Mon, 28 Sep 2026 11:30:30 +0200
Subject: [PATCH 1/3] Perf: Replace N+1 queries with optimized `WHERE IN`

Signed-off-by: Kostiantyn Miakshyn <molodchick@gmail.com>
---
 lib/Db/AnswerMapper.php                      | 23 +++++++++
 lib/Db/OptionMapper.php                      | 23 +++++++++
 lib/Service/FormsService.php                 | 13 ++++-
 lib/Service/SubmissionService.php            | 41 +++++++++++++--
 tests/Unit/Service/FormsServiceTest.php      |  4 +-
 tests/Unit/Service/SubmissionServiceTest.php | 53 ++++++++++++--------
 6 files changed, 129 insertions(+), 28 deletions(-)

diff --git a/lib/Db/AnswerMapper.php b/lib/Db/AnswerMapper.php
index 2420f6b34..6df740745 100644
--- a/lib/Db/AnswerMapper.php
+++ b/lib/Db/AnswerMapper.php
@@ -15,6 +15,7 @@
  * @extends QBMapper<Answer>
  */
 class AnswerMapper extends QBMapper {
+	private const CHUNK_SIZE = 1000;
 
 	/**
 	 * AnswerMapper constructor.
@@ -41,6 +42,28 @@ public function findBySubmission(int $submissionId): array {
 		return $this->findEntities($qb);
 	}
 
+	/**
+	 * @param list<int> $submissionIds
+	 * @return Answer[]
+	 */
+	public function findBySubmissions(array $submissionIds): array {
+		$answers = [];
+
+		foreach (array_chunk(array_unique($submissionIds), self::CHUNK_SIZE) as $submissionIdsChunk) {
+			$qb = $this->db->getQueryBuilder();
+
+			$qb->select('*')
+				->from($this->getTableName())
+				->where(
+					$qb->expr()->in('submission_id', $qb->createNamedParameter($submissionIdsChunk, IQueryBuilder::PARAM_INT_ARRAY))
+				);
+
+			$answers[] = $this->findEntities($qb);
+		}
+
+		return array_merge([], ...$answers);
+	}
+
 	/**
 	 * @param int $submissionId
 	 */
diff --git a/lib/Db/OptionMapper.php b/lib/Db/OptionMapper.php
index 2e0140dbe..ad4b4f6fb 100644
--- a/lib/Db/OptionMapper.php
+++ b/lib/Db/OptionMapper.php
@@ -10,12 +10,14 @@
 namespace OCA\Forms\Db;
 
 use OCP\AppFramework\Db\QBMapper;
+use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
 
 /**
  * @extends QBMapper<Option>
  */
 class OptionMapper extends QBMapper {
+	private const CHUNK_SIZE = 1000;
 
 	/**
 	 * OptionMapper constructor.
@@ -46,6 +48,27 @@ public function findByQuestion(int|float $questionId, ?string $optionType = null
 		return $this->findEntities($qb);
 	}
 
+	/**
+	 * @param list<int|float> $questionIds
+	 * @return Option[]
+	 */
+	public function findByQuestions(array $questionIds): array {
+		$options = [];
+		foreach (array_chunk(array_unique($questionIds), self::CHUNK_SIZE) as $questionIdsChunk) {
+			$qb = $this->db->getQueryBuilder();
+
+			$qb->select('*')
+				->from($this->getTableName())
+				->where($qb->expr()->in('question_id', $qb->createNamedParameter($questionIdsChunk, IQueryBuilder::PARAM_INT_ARRAY)))
+				->orderBy('order')
+				->addOrderBy('id');
+
+			$options[] = $this->findEntities($qb);
+		}
+
+		return array_merge([], ...$options);
+	}
+
 	public function deleteByQuestion(int $questionId): void {
 		$qb = $this->db->getQueryBuilder();
 
diff --git a/lib/Service/FormsService.php b/lib/Service/FormsService.php
index 5950ccd0c..3d5ee1713 100644
--- a/lib/Service/FormsService.php
+++ b/lib/Service/FormsService.php
@@ -11,6 +11,7 @@
 use OCA\Forms\Constants;
 use OCA\Forms\Db\Form;
 use OCA\Forms\Db\FormMapper;
+use OCA\Forms\Db\Option;
 use OCA\Forms\Db\OptionMapper;
 use OCA\Forms\Db\Question;
 use OCA\Forms\Db\QuestionMapper;
@@ -114,9 +115,19 @@ public function getQuestions(int $formId): array {
 		$questionList = [];
 		try {
 			$questionEntities = $this->questionMapper->findByForm($formId);
+
+			$questionIds = array_map(static fn (Question $question) => $question->getId(), $questionEntities);
+			$optionsByQuestion = [];
+			foreach ($this->optionMapper->findByQuestions($questionIds) as $optionEntity) {
+				$optionsByQuestion[$optionEntity->getQuestionId()][] = $optionEntity;
+			}
+
 			foreach ($questionEntities as $questionEntity) {
 				$question = $questionEntity->read();
-				$question['options'] = $this->getOptions($question['id']);
+				$question['options'] = array_map(
+					static fn (Option $option) => $option->read(),
+					$optionsByQuestion[$question['id']] ?? []
+				);
 				$question['accept'] = [];
 				if ($question['type'] === Constants::ANSWER_TYPE_FILE) {
 					if ($question['extraSettings']['allowedFileTypes'] ?? null) {
diff --git a/lib/Service/SubmissionService.php b/lib/Service/SubmissionService.php
index ff733998e..f9c626583 100644
--- a/lib/Service/SubmissionService.php
+++ b/lib/Service/SubmissionService.php
@@ -17,6 +17,7 @@
 use OCA\Forms\Db\OptionMapper;
 use OCA\Forms\Db\Question;
 use OCA\Forms\Db\QuestionMapper;
+use OCA\Forms\Db\Submission;
 use OCA\Forms\Db\SubmissionMapper;
 use OCA\Forms\Db\UploadedFileMapper;
 use OCA\Forms\ResponseDefinitions;
@@ -110,9 +111,18 @@ public function getSubmissions(int $formId, ?string $userId = null, ?string $que
 		try {
 			$submissionEntities = $this->submissionMapper->findByForm($formId, $userId, $query, $limit, $offset);
 
+			$submissionIds = array_map(static fn (Submission $submission) => $submission->getId(), $submissionEntities);
+			$answersBySubmission = [];
+			foreach ($this->answerMapper->findBySubmissions($submissionIds) as $answer) {
+				$answersBySubmission[$answer->getSubmissionId()][] = $answer;
+			}
+
 			foreach ($submissionEntities as $submissionEntity) {
 				$submission = $submissionEntity->read();
-				$submission['answers'] = $this->getAnswers($submission['id']);
+				$submission['answers'] = array_map(
+					static fn (Answer $answer) => $answer->read(),
+					$answersBySubmission[$submission['id']] ?? []
+				);
 				$submissionList[] = $submission;
 			}
 		} catch (DoesNotExistException) {
@@ -221,6 +231,7 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			throw new \InvalidArgumentException('Invalid file format');
 		}
 
+		$submissionEntities = [];
 		try {
 			$submissionEntities = $this->submissionMapper->findByForm($form->getId());
 		} catch (DoesNotExistException) {
@@ -239,6 +250,26 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			$userTimezone = $this->userConfig->getValueString($this->currentUser->getUID(), 'core', 'timezone', $defaultTimeZone);
 		}
 
+		// Fetch all answers of the loaded submissions at once, grouped by submission
+		$submissionIds = array_map(static fn (Submission $submission) => $submission->getId(), $submissionEntities);
+		$answersBySubmission = [];
+		foreach ($this->answerMapper->findBySubmissions($submissionIds) as $answer) {
+			$answersBySubmission[$answer->getSubmissionId()][] = $answer;
+		}
+
+		// Resolve each submitting user only once
+		$usersById = [];
+		foreach (array_unique(array_map(static fn (Submission $submission) => $submission->getUserId(), $submissionEntities)) as $userId) {
+			$usersById[$userId] = $this->userManager->get($userId);
+		}
+
+		// Fetch all options of the form's questions at once, grouped by question
+		$questionIds = array_map(static fn (Question $question) => $question->getId(), $questions);
+		$optionsByQuestion = [];
+		foreach ($this->optionMapper->findByQuestions($questionIds) as $option) {
+			$optionsByQuestion[$option->getQuestionId()][] = $option;
+		}
+
 		// Process initial header
 		$header = [];
 		$header[] = ['id' => 'submission_id', 'title' => $this->l10n->t('Submission ID')];
@@ -258,7 +289,7 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 		foreach ($questions as $question) {
 			if ($question->getType() === Constants::ANSWER_TYPE_GRID) {
 				$gridCellType = $question->getExtraSettings()['questionType'];
-				$options = $this->optionMapper->findByQuestion($question->getId());
+				$options = $optionsByQuestion[$question->getId()] ?? [];
 
 				foreach ($options as $option) {
 					$optionPerOptionId[$option->getId()] = $option;
@@ -282,7 +313,7 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 					}
 				}
 			} elseif ($question->getType() === Constants::ANSWER_TYPE_RANKING) {
-				$options = $this->optionMapper->findByQuestion($question->getId());
+				$options = $optionsByQuestion[$question->getId()] ?? [];
 				foreach ($options as $option) {
 					$optionPerOptionId[$option->getId()] = $option;
 					$rankingOptionsPerQuestionId[$question->getId()][] = $option->getId();
@@ -307,7 +338,7 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			$row[] = $submission->getId();
 
 			// User
-			$user = $this->userManager->get($submission->getUserId());
+			$user = $usersById[$submission->getUserId()] ?? null;
 			if ($user === null) {
 				// Give empty userId
 				$row[] = '';
@@ -322,7 +353,7 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			$row[] = date_format(date_timestamp_set(new DateTime(), $submission->getTimestamp())->setTimezone(new DateTimeZone($userTimezone)), 'c');
 
 			// Answers, make sure we keep the question order
-			$answers = array_reduce($this->answerMapper->findBySubmission($submission->getId()),
+			$answers = array_reduce($answersBySubmission[$submission->getId()] ?? [],
 				function (array $carry, Answer $answer) use ($questionPerQuestionId, $gridRowsPerQuestionId, $gridColumnsPerQuestionId, $rankingOptionsPerQuestionId, $optionPerOptionId) {
 					$questionId = $answer->getQuestionId();
 					$questionType = isset($questionPerQuestionId[$questionId]) ? $questionPerQuestionId[$questionId]->getType() : null;
diff --git a/tests/Unit/Service/FormsServiceTest.php b/tests/Unit/Service/FormsServiceTest.php
index ea9707814..323929be9 100644
--- a/tests/Unit/Service/FormsServiceTest.php
+++ b/tests/Unit/Service/FormsServiceTest.php
@@ -342,8 +342,8 @@ public function testGetForm(array $expected) {
 		$option2->setQuestionId(1);
 		$option2->setText('Option 2');
 		$this->optionMapper->expects($this->any())
-			->method('findByQuestion')
-			->with(1)
+			->method('findByQuestions')
+			->with([1, 2])
 			->willReturn([$option1, $option2]);
 
 		$share = new Share();
diff --git a/tests/Unit/Service/SubmissionServiceTest.php b/tests/Unit/Service/SubmissionServiceTest.php
index ddc2d23b4..afe85a579 100644
--- a/tests/Unit/Service/SubmissionServiceTest.php
+++ b/tests/Unit/Service/SubmissionServiceTest.php
@@ -150,11 +150,13 @@ public function testGetSubmissions() {
 			});
 
 		$this->answerMapper->expects($this->any())
-			->method('findBySubmission')
-			->willReturnMap([
-				[42, [$answer_1, $answer_2]],
-				[43, []]
-			]);
+			->method('findBySubmissions')
+			->willReturnCallback(function (array $submissionIds) use ($answer_1, $answer_2) {
+				if (in_array(42, $submissionIds, true)) {
+					return [$answer_1, $answer_2];
+				}
+				return [];
+			});
 
 		$expected = [
 			[
@@ -749,16 +751,21 @@ private function setUpCsvTest(array $questions, array $submissions, string $csvT
 				return $questionEntities;
 			}));
 
-		if (!empty($questions[0]['options'])) {
-			$this->optionMapper->expects($this->once())
-				->method('findByQuestion')
-				->with($questions[0]['id'])
-				->willReturnCallback(function (int $questionId) use ($questions) {
-					$optionsEntities = array_map(fn ($option) => Option::fromParams($option), $questions[0]['options']);
+		$this->optionMapper->expects($this->any())
+			->method('findByQuestions')
+			->willReturnCallback(function (array $questionIds) use ($questions) {
+				$optionsEntities = [];
+				foreach ($questions as $question) {
+					if (!in_array($question['id'], $questionIds, true)) {
+						continue;
+					}
+					foreach ($question['options'] ?? [] as $option) {
+						$optionsEntities[] = Option::fromParams(array_merge($option, ['questionId' => $question['id']]));
+					}
+				}
 
-					return $optionsEntities;
-				});
-		}
+				return $optionsEntities;
+			});
 
 		$this->config->expects($this->once())
 			->method('getSystemValueString')
@@ -786,12 +793,18 @@ private function setUpCsvTest(array $questions, array $submissions, string $csvT
 			]);
 
 		$this->answerMapper->expects($this->any())
-			->method('findBySubmission')
-		// Return AnswerObjects for corresponding submission
-			->will($this->returnCallback(function (int $submissionId) use ($submissions) {
-				$matchingSubmission = array_filter($submissions, fn ($submission) => $submission['id'] === $submissionId);
-
-				$answerEntities = array_map(fn ($answer) => Answer::fromParams($answer), current($matchingSubmission)['answers']);
+			->method('findBySubmissions')
+		// Return AnswerObjects for corresponding submissions
+			->will($this->returnCallback(function (array $submissionIds) use ($submissions) {
+				$answerEntities = [];
+				foreach ($submissions as $submission) {
+					if (!in_array($submission['id'], $submissionIds, true)) {
+						continue;
+					}
+					foreach ($submission['answers'] as $answer) {
+						$answerEntities[] = Answer::fromParams(array_merge($answer, ['submissionId' => $submission['id']]));
+					}
+				}
 
 				return $answerEntities;
 			}));

From e5c24eb0c397ae8d22bc5bccd8fab2f38474f495 Mon Sep 17 00:00:00 2001
From: Kostiantyn Miakshyn <molodchick@gmail.com>
Date: Mon, 28 Sep 2026 13:57:50 +0200
Subject: [PATCH 2/3] Perf: Replace N+1 queries with optimized `WHERE IN`
 (cache usernames)

Signed-off-by: Kostiantyn Miakshyn <molodchick@gmail.com>
---
 appinfo/info.xml                             |  2 +-
 lib/Controller/ApiController.php             | 20 ++++----------------
 lib/Service/SubmissionService.php            | 15 ++++++++-------
 tests/Unit/Controller/ApiControllerTest.php  |  8 +++-----
 tests/Unit/Service/SubmissionServiceTest.php | 17 +++++------------
 5 files changed, 21 insertions(+), 41 deletions(-)

diff --git a/appinfo/info.xml b/appinfo/info.xml
index c979b1b43..e35320e25 100644
--- a/appinfo/info.xml
+++ b/appinfo/info.xml
@@ -61,7 +61,7 @@
 	<screenshot>https://raw.githubusercontent.com/nextcloud/forms/main/screenshots/forms3.png</screenshot>
 
 	<dependencies>
-		<nextcloud min-version="33" max-version="35" />
+		<nextcloud min-version="33" max-version="36" />
 	</dependencies>
 
 	<background-jobs>
diff --git a/lib/Controller/ApiController.php b/lib/Controller/ApiController.php
index 6b54111fa..c6b3dc574 100644
--- a/lib/Controller/ApiController.php
+++ b/lib/Controller/ApiController.php
@@ -1283,14 +1283,8 @@ public function getSubmissions(int $formId, ?string $query = null, ?int $limit =
 				// TRANSLATORS On Results when listing the single Responses to the form, this text is shown as heading of the Response.
 				$submission['userDisplayName'] = $this->l10n->t('Anonymous response');
 			} else {
-				$userEntity = $this->userManager->get($submission['userId']);
-
-				if ($userEntity instanceof IUser) {
-					$submission['userDisplayName'] = $userEntity->getDisplayName();
-				} else {
-					// Fallback, should not occur regularly.
-					$submission['userDisplayName'] = $submission['userId'];
-				}
+				// Fallback to the userId, should not occur regularly.
+				$submission['userDisplayName'] = $this->userManager->getDisplayName($submission['userId']) ?? $submission['userId'];
 			}
 			return $submission;
 		}, $submissions);
@@ -1352,14 +1346,8 @@ public function getSubmission(int $formId, int $submissionId): DataResponse|Data
 			// TRANSLATORS On Results when listing the single Responses to the form, this text is shown as heading of the Response.
 			$submission['userDisplayName'] = $this->l10n->t('Anonymous response');
 		} else {
-			$userEntity = $this->userManager->get($submission['userId']);
-
-			if ($userEntity instanceof IUser) {
-				$submission['userDisplayName'] = $userEntity->getDisplayName();
-			} else {
-				// Fallback, should not occur regularly.
-				$submission['userDisplayName'] = $submission['userId'];
-			}
+			// Fallback to the userId, should not occur regularly.
+			$submission['userDisplayName'] = $this->userManager->getDisplayName($submission['userId']) ?? $submission['userId'];
 		}
 
 		return new DataResponse($submission);
diff --git a/lib/Service/SubmissionService.php b/lib/Service/SubmissionService.php
index f9c626583..278fb2828 100644
--- a/lib/Service/SubmissionService.php
+++ b/lib/Service/SubmissionService.php
@@ -257,10 +257,10 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			$answersBySubmission[$answer->getSubmissionId()][] = $answer;
 		}
 
-		// Resolve each submitting user only once
-		$usersById = [];
+		// Resolve each submitting user's display name only once
+		$userDisplayNames = [];
 		foreach (array_unique(array_map(static fn (Submission $submission) => $submission->getUserId(), $submissionEntities)) as $userId) {
-			$usersById[$userId] = $this->userManager->get($userId);
+			$userDisplayNames[$userId] = $this->userManager->getDisplayName($userId);
 		}
 
 		// Fetch all options of the form's questions at once, grouped by question
@@ -338,15 +338,16 @@ public function getSubmissionsData(Form $form, string $fileFormat, ?File $file =
 			$row[] = $submission->getId();
 
 			// User
-			$user = $usersById[$submission->getUserId()] ?? null;
-			if ($user === null) {
+			$userId = $submission->getUserId();
+			$displayName = $userDisplayNames[$userId] ?? null;
+			if ($displayName === null) {
 				// Give empty userId
 				$row[] = '';
 				// TRANSLATORS Shown on export if no Display-Name is available.
 				$row[] = $this->l10n->t('Anonymous user');
 			} else {
-				$row[] = $user->getUID();
-				$row[] = $user->getDisplayName();
+				$row[] = $userId;
+				$row[] = $displayName;
 			}
 
 			// Date
diff --git a/tests/Unit/Controller/ApiControllerTest.php b/tests/Unit/Controller/ApiControllerTest.php
index 92a6096d7..d64499640 100644
--- a/tests/Unit/Controller/ApiControllerTest.php
+++ b/tests/Unit/Controller/ApiControllerTest.php
@@ -1528,12 +1528,10 @@ public function testGetSubmission_success() {
 			->with(42)
 			->willReturn($submissionDataFromService); // Service returns an array
 
-		$user = $this->createMock(IUser::class);
-		$user->method('getDisplayName')->willReturn('jdoe');
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('jdoe')
-			->willReturn($user);
+			->willReturn('jdoe');
 
 		$expectedSubmissionInResponse = $submissionDataFromService;
 		$expectedSubmissionInResponse['userDisplayName'] = 'jdoe';
@@ -1635,7 +1633,7 @@ public function testGetSubmission_userNotFound() {
 			->willReturn($submissionDataFromService); // Service returns an array
 
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('nonExistentUser')
 			->willReturn(null);
 
diff --git a/tests/Unit/Service/SubmissionServiceTest.php b/tests/Unit/Service/SubmissionServiceTest.php
index afe85a579..5a14199b1 100644
--- a/tests/Unit/Service/SubmissionServiceTest.php
+++ b/tests/Unit/Service/SubmissionServiceTest.php
@@ -390,8 +390,8 @@ public static function dataGetSubmissionsData() {
 				'
 				"Submission ID","User ID","User display name","Timestamp","Question 1","Question 2"
 				"submission_id","user_id","user_display_name","timestamp","question-id-1","question-id-2"
-				"2","user1","User 1","1973-11-29T22:33:09+01:00","Q1A2","Q2A2"
-				"1","user2","User 2","1973-11-29T22:33:09+01:00","Q1A1","Q2A1"
+				"2","user2","User 2","1973-11-29T22:33:09+01:00","Q1A2","Q2A2"
+				"1","user1","User 1","1973-11-29T22:33:09+01:00","Q1A1","Q2A1"
 				'
 			],
 			'checkbox-multi-answers' => [
@@ -777,18 +777,11 @@ private function setUpCsvTest(array $questions, array $submissions, string $csvT
 			->with('currentUser', 'core', 'timezone', 'Europe/Berlin')
 			->willReturn('Europe/Berlin');
 
-		$user = $this->createMock(IUser::class);
-		$user->expects($this->any())
-			->method('getUID')
-			->will($this->onConsecutiveCalls('user1', 'user2'));
-		$user->expects($this->any())
-			->method('getDisplayName')
-			->will($this->onConsecutiveCalls('User 1', 'User 2'));
 		$this->userManager->expects($this->any())
-			->method('get')
+			->method('getDisplayName')
 			->willReturnMap([
-				['user1', $user],
-				['user2', $user],
+				['user1', 'User 1'],
+				['user2', 'User 2'],
 				['unknown', null]
 			]);
 

From 8fb862693d2cbee2b32d24297cf62102af01e8e0 Mon Sep 17 00:00:00 2001
From: Kostiantyn Miakshyn <molodchick@gmail.com>
Date: Mon, 28 Sep 2026 14:39:08 +0200
Subject: [PATCH 3/3] Perf: Replace N+1 queries with optimized `WHERE IN` (try
 fix pipeline)

Signed-off-by: Kostiantyn Miakshyn <molodchick@gmail.com>
---
 appinfo/info.xml                              |  2 +-
 .../CleanupUploadedFilesJobTest.php           |  6 ++++-
 tests/Unit/Controller/ApiControllerTest.php   |  7 ++++--
 .../Controller/ShareApiControllerTest.php     |  6 +++--
 tests/Unit/Helper/FilePathHelperTest.php      | 19 ++++++++-------
 tests/Unit/Service/FormsServiceTest.php       |  5 ++--
 tests/Unit/Service/SubmissionServiceTest.php  |  4 +++-
 .../Service/UploadedFilesShareServiceTest.php |  7 ++++--
 tests/Unit/UserFolderMockTrait.php            | 24 +++++++++++++++++++
 9 files changed, 61 insertions(+), 19 deletions(-)
 create mode 100644 tests/Unit/UserFolderMockTrait.php

diff --git a/appinfo/info.xml b/appinfo/info.xml
index e35320e25..c979b1b43 100644
--- a/appinfo/info.xml
+++ b/appinfo/info.xml
@@ -61,7 +61,7 @@
 	<screenshot>https://raw.githubusercontent.com/nextcloud/forms/main/screenshots/forms3.png</screenshot>
 
 	<dependencies>
-		<nextcloud min-version="33" max-version="36" />
+		<nextcloud min-version="33" max-version="35" />
 	</dependencies>
 
 	<background-jobs>
diff --git a/tests/Unit/BackgroundJob/CleanupUploadedFilesJobTest.php b/tests/Unit/BackgroundJob/CleanupUploadedFilesJobTest.php
index 8bc5e36cf..86d108fba 100644
--- a/tests/Unit/BackgroundJob/CleanupUploadedFilesJobTest.php
+++ b/tests/Unit/BackgroundJob/CleanupUploadedFilesJobTest.php
@@ -13,6 +13,7 @@
 use OCA\Forms\Db\FormMapper;
 use OCA\Forms\Db\UploadedFile;
 use OCA\Forms\Db\UploadedFileMapper;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Files\IRootFolder;
 use PHPUnit\Framework\MockObject\MockObject;
@@ -20,6 +21,8 @@
 use Test\TestCase;
 
 class CleanupUploadedFilesJobTest extends TestCase {
+	use UserFolderMockTrait;
+
 	private IRootFolder|MockObject $rootFolder;
 	private CleanupUploadedFilesJob $cleanupUploadedFilesJob;
 	private FormMapper|MockObject $formMapper;
@@ -60,9 +63,10 @@ public function testHandle() {
 			->method('findUploadedEarlierThan')
 			->willReturn([$uploadedFile]);
 
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->atLeastOnce())
 			->method('getUserFolder')
-			->willReturn($this->rootFolder);
+			->willReturn($userFolder);
 
 		$this->cleanupUploadedFilesJob->run([]);
 	}
diff --git a/tests/Unit/Controller/ApiControllerTest.php b/tests/Unit/Controller/ApiControllerTest.php
index d64499640..c3c0bbde1 100644
--- a/tests/Unit/Controller/ApiControllerTest.php
+++ b/tests/Unit/Controller/ApiControllerTest.php
@@ -47,6 +47,7 @@ function is_uploaded_file(string|bool|null $filename) {
 use OCA\Forms\Service\ConfirmationEmailService;
 use OCA\Forms\Service\FormsService;
 use OCA\Forms\Service\SubmissionService;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataDownloadResponse;
@@ -71,6 +72,8 @@ function is_uploaded_file(string|bool|null $filename) {
 use Test\TestCase;
 
 class ApiControllerTest extends TestCase {
+	use UserFolderMockTrait;
+
 	private ApiController $apiController;
 	private AnswerMapper|MockObject $answerMapper;
 	private FormMapper|MockObject $formMapper;
@@ -714,7 +717,7 @@ public function testUploadFiles() {
 
 		\OCA\Forms\Controller\is_uploaded_file(true);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->expects($this->once())
 			->method('nodeExists')
 			->willReturn(true);
@@ -848,7 +851,7 @@ public function testNewSubmission_answers() {
 			->method('add')
 			->with(SyncSubmissionsWithLinkedFileJob::class, ['form_id' => 1]);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->expects($this->once())
 			->method('nodeExists')
 			->willReturn(true);
diff --git a/tests/Unit/Controller/ShareApiControllerTest.php b/tests/Unit/Controller/ShareApiControllerTest.php
index 990cafd5b..42099d651 100644
--- a/tests/Unit/Controller/ShareApiControllerTest.php
+++ b/tests/Unit/Controller/ShareApiControllerTest.php
@@ -21,6 +21,7 @@
 use OCA\Forms\Service\ConfigService;
 use OCA\Forms\Service\FormsService;
 use OCA\Forms\Service\UploadedFilesShareService;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Db\IMapperException;
 use OCP\AppFramework\Http;
@@ -49,6 +50,7 @@ interface MapperException extends Throwable, IMapperException {
 };
 
 class ShareApiControllerTest extends TestCase {
+	use UserFolderMockTrait;
 
 	private ShareApiController $shareApiController;
 	private FormMapper|MockObject $formMapper;
@@ -545,7 +547,7 @@ public function testDeleteShare_cleansUpFileShare(): void {
 
 		// Mock the uploaded files folder lookup
 		$folder = $this->createMock(Folder::class);
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->expects($this->once())
 			->method('get')
 			->willReturn($folder);
@@ -837,7 +839,7 @@ public function testUpdateShare(array $share, string $formOwner, array $keyValue
 			->with('otherUser')
 			->willReturn($this->createMock(IUser::class));
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 
 		$file = $this->createMock(File::class);
 		$file->expects($this->any())
diff --git a/tests/Unit/Helper/FilePathHelperTest.php b/tests/Unit/Helper/FilePathHelperTest.php
index 82d408de5..41769e4c2 100644
--- a/tests/Unit/Helper/FilePathHelperTest.php
+++ b/tests/Unit/Helper/FilePathHelperTest.php
@@ -10,6 +10,7 @@
 use OCA\Forms\Constants;
 use OCA\Forms\Db\Form;
 use OCA\Forms\Helper\FilePathHelper;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\Files\Folder;
 use OCP\Files\IFilenameValidator;
 use OCP\Files\IRootFolder;
@@ -18,6 +19,8 @@
 use Test\TestCase;
 
 class FilePathHelperTest extends TestCase {
+	use UserFolderMockTrait;
+
 	private FilePathHelper $filePathHelper;
 	private IFilenameValidator|MockObject $filenameValidator;
 	private IRootFolder|MockObject $rootFolder;
@@ -86,7 +89,7 @@ public function testGetUploadedFilePathWithoutQuestionName() {
 	}
 
 	public function testGetFormsFolderReturnsFolder() {
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$formsFolder = $this->createMock(Folder::class);
 
 		$this->rootFolder->expects($this->once())
@@ -104,7 +107,7 @@ public function testGetFormsFolderReturnsFolder() {
 	}
 
 	public function testGetFormsFolderReturnsNullWhenNotFound() {
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
@@ -121,7 +124,7 @@ public function testGetFormsFolderReturnsNullWhenNotFound() {
 	}
 
 	public function testGetFormsFolderReturnsNullWhenNotFolder() {
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$notAFolder = $this->createMock(\OCP\Files\File::class);
 
 		$this->rootFolder->expects($this->once())
@@ -155,7 +158,7 @@ public function testGetAllFormFoldersById() {
 		]);
 
 		// Mock getFormsFolder to return our formsFolder
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
 			->with('user1')
@@ -174,7 +177,7 @@ public function testGetAllFormFoldersById() {
 	}
 
 	public function testGetAllFormFoldersByIdReturnsEmptyWhenFormsFolderNull() {
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
 			->with('user1')
@@ -201,7 +204,7 @@ public function testGetSubmissionFolder() {
 		$formFolder->method('getName')->willReturn('42 - Form Title');
 		$formsFolder->method('getDirectoryListing')->willReturn([$formFolder]);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
 			->with('user1')
@@ -232,7 +235,7 @@ public function testGetSubmissionFolderReturnsNullWhenNotFound() {
 		$formFolder->method('getName')->willReturn('42 - Form Title');
 		$formsFolder->method('getDirectoryListing')->willReturn([$formFolder]);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
 			->with('user1')
@@ -264,7 +267,7 @@ public function testGetSubmissionFolderReturnsNullWhenNotFolder() {
 		$formFolder->method('getName')->willReturn('42 - Form Title');
 		$formsFolder->method('getDirectoryListing')->willReturn([$formFolder]);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$this->rootFolder->expects($this->once())
 			->method('getUserFolder')
 			->with('user1')
diff --git a/tests/Unit/Service/FormsServiceTest.php b/tests/Unit/Service/FormsServiceTest.php
index 323929be9..c8a059db7 100644
--- a/tests/Unit/Service/FormsServiceTest.php
+++ b/tests/Unit/Service/FormsServiceTest.php
@@ -46,9 +46,9 @@ function microtime(bool|float $asFloat = false) {
 use OCA\Forms\Service\ConfigService;
 use OCA\Forms\Service\ConfirmationEmailService;
 use OCA\Forms\Service\FormsService;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\EventDispatcher\IEventDispatcher;
-use OCP\Files\Folder;
 use OCP\Files\IFilenameValidator;
 use OCP\Files\IRootFolder;
 use OCP\Files\NotFoundException;
@@ -66,6 +66,7 @@ function microtime(bool|float $asFloat = false) {
 use Test\TestCase;
 
 class FormsServiceTest extends TestCase {
+	use UserFolderMockTrait;
 
 	private FormsService $formsService;
 	private ActivityManager|MockObject $activityManager;
@@ -1652,7 +1653,7 @@ public function testGetFilePathThrowsAnException() {
 		$form->setFileId(100);
 		$form->setOwnerId('user1');
 
-		$folder = $this->createMock(Folder::class);
+		$folder = $this->createUserFolderMock();
 		$folder->expects($this->once())
 			->method('getById')
 			->with(100)
diff --git a/tests/Unit/Service/SubmissionServiceTest.php b/tests/Unit/Service/SubmissionServiceTest.php
index 5a14199b1..e3d19a7e4 100644
--- a/tests/Unit/Service/SubmissionServiceTest.php
+++ b/tests/Unit/Service/SubmissionServiceTest.php
@@ -22,6 +22,7 @@
 use OCA\Forms\Db\UploadedFileMapper;
 use OCA\Forms\Service\FormsService;
 use OCA\Forms\Service\SubmissionService;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\Config\IUserConfig;
 use OCP\Files\File;
@@ -43,6 +44,7 @@
 use Test\TestCase;
 
 class SubmissionServiceTest extends TestCase {
+	use UserFolderMockTrait;
 
 	private SubmissionService $submissionService;
 	private FormMapper|MockObject $formMapper;
@@ -325,7 +327,7 @@ public function testWriteFileToCloud(string $formTitle, string $path, string $pa
 			$pathNode = $folderNode;
 		}
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->expects($this->once())
 			->method('get')
 			->with($path)
diff --git a/tests/Unit/Service/UploadedFilesShareServiceTest.php b/tests/Unit/Service/UploadedFilesShareServiceTest.php
index 24ad72712..807b51233 100644
--- a/tests/Unit/Service/UploadedFilesShareServiceTest.php
+++ b/tests/Unit/Service/UploadedFilesShareServiceTest.php
@@ -15,6 +15,7 @@
 use OCA\Forms\Db\ShareMapper;
 use OCA\Forms\Helper\FilePathHelper;
 use OCA\Forms\Service\UploadedFilesShareService;
+use OCA\Forms\Tests\Unit\UserFolderMockTrait;
 use OCP\Files\Folder;
 use OCP\Files\IFilenameValidator;
 use OCP\Files\IRootFolder;
@@ -26,6 +27,8 @@
 use Test\TestCase;
 
 class UploadedFilesShareServiceTest extends TestCase {
+	use UserFolderMockTrait;
+
 	private UploadedFilesShareService $service;
 	private ShareMapper|MockObject $shareMapper;
 	private IRootFolder|MockObject $rootFolder;
@@ -75,7 +78,7 @@ public function testRemoveAllForFormCleansUpResultsShares(): void {
 			->willReturn([$resultsShare, $submitOnlyShare]);
 
 		$folder = $this->createMock(Folder::class);
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->expects($this->once())
 			->method('get')
 			->with('Forms/2 - test')
@@ -125,7 +128,7 @@ public function testRemoveForCollaboratorIgnoresMissingUploadedFilesFolder(): vo
 		$share->setShareWith('bob');
 		$share->setPermissions([Constants::PERMISSION_RESULTS]);
 
-		$userFolder = $this->createMock(Folder::class);
+		$userFolder = $this->createUserFolderMock();
 		$userFolder->method('get')->willThrowException(new NotFoundException());
 		$this->rootFolder->method('getUserFolder')->with('alice')->willReturn($userFolder);
 		$this->shareManager->expects($this->never())->method('getSharesBy');
diff --git a/tests/Unit/UserFolderMockTrait.php b/tests/Unit/UserFolderMockTrait.php
new file mode 100644
index 000000000..cc9fb78e9
--- /dev/null
+++ b/tests/Unit/UserFolderMockTrait.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Forms\Tests\Unit;
+
+use OCP\Files\Folder;
+use OCP\Files\IUserFolder;
+use PHPUnit\Framework\MockObject\MockObject;
+
+/**
+ * IRootFolder::getUserFolder() is typed as IUserFolder since Nextcloud 36,
+ * older versions expect a Folder. Mock whichever interface exists.
+ */
+trait UserFolderMockTrait {
+	private function createUserFolderMock(): Folder&MockObject {
+		$className = interface_exists(IUserFolder::class) ? IUserFolder::class : Folder::class;
+		return $this->createMock($className);
+	}
+}