Make DisplayNameCache return null if user doesn't exists

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

3 files changed, 4 insertions, 4 deletions

diff --git a/lib/private/User/DisplayNameCache.php b/lib/private/User/DisplayNameCache.php
index 22a79863e49..5d1cc8940d7 100644
--- a/lib/private/User/DisplayNameCache.php
+++ b/lib/private/User/DisplayNameCache.php
@@ -47,7 +47,7 @@ class DisplayNameCache implements IEventListener {
 		$this->userManager = $userManager;
 	}
 
-	public function getDisplayName(string $userId) {
+	public function getDisplayName(string $userId): ?string {
 		if (isset($this->cache[$userId])) {
 			return $this->cache[$userId];
 		}
@@ -61,7 +61,7 @@ class DisplayNameCache implements IEventListener {
 		if ($user) {
 			$displayName = $user->getDisplayName();
 		} else {
-			$displayName = $userId;
+			$displayName = null;
 		}
 		$this->cache[$userId] = $displayName;
 		$this->memCache->set($userId, $displayName, 60 * 10); // 10 minutes
diff --git a/lib/private/User/LazyUser.php b/lib/private/User/LazyUser.php
index 118dd3d0699..096578b8f37 100644
--- a/lib/private/User/LazyUser.php
+++ b/lib/private/User/LazyUser.php
@@ -51,7 +51,7 @@ class LazyUser implements IUser {
 	}
 
 	public function getDisplayName() {
-		return $this->userManager->getDisplayName($this->uid);
+		return $this->userManager->getDisplayName($this->uid) ?? $this->uid;
 	}
 
 	public function setDisplayName($displayName) {
diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index 55ac663f3ec..be5151313c4 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -188,7 +188,7 @@ class Manager extends PublicEmitter implements IUserManager {
 		return null;
 	}
 
-	public function getDisplayName(string $uid): string {
+	public function getDisplayName(string $uid): ?string {
 		return $this->displayNameCache->getDisplayName($uid);
 	}