From c8f3c0423e7a3d36d8e19427f23ebfec2eede841 Mon Sep 17 00:00:00 2001
From: Peter Ringelmann <peter.ringelmann@nextcloud.com>
Date: Thu, 2 Apr 2026 18:03:19 +0200
Subject: [PATCH] fix(provisioning_api): allow clearing display name via
 editUserMultiField

Map empty string to userId since User::setDisplayName() rejects ""
-e
Signed-off-by: Peter Ringelmann <peter.ringelmann@nextcloud.com>
---
 .../lib/Controller/UsersController.php        |  4 +++-
 .../tests/Controller/UsersControllerTest.php  | 23 +++++++++++++++++++
 .../components/Users/userFormUtils.spec.ts    | 12 ++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/apps/provisioning_api/lib/Controller/UsersController.php b/apps/provisioning_api/lib/Controller/UsersController.php
index 67e391ba491..e398d7b4c9f 100644
--- a/apps/provisioning_api/lib/Controller/UsersController.php
+++ b/apps/provisioning_api/lib/Controller/UsersController.php
@@ -1078,7 +1078,9 @@ class UsersController extends AUserDataOCSController
 
 		// Apply remaining changes — all fully validated, setters won't throw
 		if ($displayName !== null) {
-			$targetUser->setDisplayName($displayName);
+			// OC\User\User::setDisplayName() rejects empty strings (!empty check),
+			// so "clear display name" means "reset to userId" — the default.
+			$targetUser->setDisplayName($displayName !== '' ? $displayName : $userId);
 		}
 
 		if ($email !== null) {
diff --git a/apps/provisioning_api/tests/Controller/UsersControllerTest.php b/apps/provisioning_api/tests/Controller/UsersControllerTest.php
index ce4b77d22e1..e4eec967c99 100644
--- a/apps/provisioning_api/tests/Controller/UsersControllerTest.php
+++ b/apps/provisioning_api/tests/Controller/UsersControllerTest.php
@@ -2852,6 +2852,29 @@ class UsersControllerTest extends TestCase {
 		$this->assertArrayHasKey('language', $result->getData()['errors']);
 	}
 
+	public function testEditUserMultiFieldClearDisplayNameResetsToUserId(): void {
+		$currentUser = $this->createMock(IUser::class);
+		$currentUser->method('getUID')->willReturn('admin');
+		$this->userSession->method('getUser')->willReturn($currentUser);
+
+		$targetUser = $this->createMock(IUser::class);
+		$targetUser->method('getUID')->willReturn('targetuser');
+		$targetUser->method('canChangeDisplayName')->willReturn(true);
+		$targetUser->method('getBackend')->willReturn($this->createMock(UserInterface::class));
+		$this->userManager->method('get')->with('targetuser')->willReturn($targetUser);
+
+		$this->groupManager->method('isAdmin')->with('admin')->willReturn(true);
+		$this->groupManager->method('isDelegatedAdmin')->willReturn(false);
+		$subAdmin = $this->createMock(ISubAdmin::class);
+		$this->groupManager->method('getSubAdmin')->willReturn($subAdmin);
+
+		// Clearing display name (empty string) should reset to userId
+		$targetUser->expects($this->once())->method('setDisplayName')->with('targetuser')->willReturn(true);
+
+		$result = $this->api->editUserMultiField('targetuser', displayName: '');
+		$this->assertSame(Http::STATUS_OK, $result->getStatus());
+	}
+
 
 	public function testDeleteUserNotExistingUser(): void {
 		$this->expectException(OCSException::class);
diff --git a/apps/settings/src/components/Users/userFormUtils.spec.ts b/apps/settings/src/components/Users/userFormUtils.spec.ts
index adf1cb3da3f..01482e30e71 100644
--- a/apps/settings/src/components/Users/userFormUtils.spec.ts
+++ b/apps/settings/src/components/Users/userFormUtils.spec.ts
@@ -153,6 +153,18 @@ describe('diffPayload', () => {
 		expect(diffPayload(initial, current)).toEqual({ displayName: 'Robert' })
 	})
 
+	it('detects displayName cleared to empty string', () => {
+		const initial = makeFormData({ displayName: 'Bob' })
+		const current = makeFormData({ displayName: '' })
+		expect(diffPayload(initial, current)).toEqual({ displayName: '' })
+	})
+
+	it('detects email cleared to empty string', () => {
+		const initial = makeFormData({ email: 'bob@example.com' })
+		const current = makeFormData({ email: '' })
+		expect(diffPayload(initial, current)).toEqual({ email: '' })
+	})
+
 	it('always includes password when non-empty', () => {
 		const initial = makeFormData()
 		const current = makeFormData({ password: 'secret123' })