diff --git a/lib/Db/AssignmentMapper.php b/lib/Db/AssignmentMapper.php
index 816276ace..44aa178df 100644
--- a/lib/Db/AssignmentMapper.php
+++ b/lib/Db/AssignmentMapper.php
@@ -144,8 +144,8 @@ class AssignmentMapper extends QBMapper implements IPermissionMapper {
 
 	private function getOrigin(Assignment $assignment) {
 		if ($assignment->getType() === Assignment::TYPE_USER) {
-			$origin = $this->userManager->get($assignment->getParticipant());
-			return $origin ? new User($origin) : null;
+			$origin = $this->userManager->userExists($assignment->getParticipant());
+			return $origin ? new User($assignment->getParticipant(), $this->userManager) : null;
 		}
 		if ($assignment->getType() === Assignment::TYPE_GROUP) {
 			$origin = $this->groupManager->get($assignment->getParticipant());
diff --git a/lib/Db/BoardMapper.php b/lib/Db/BoardMapper.php
index 5db3c3994..cb5d2c38d 100644
--- a/lib/Db/BoardMapper.php
+++ b/lib/Db/BoardMapper.php
@@ -455,13 +455,11 @@ class BoardMapper extends QBMapper implements IPermissionMapper {
 	}
 
 	public function mapAcl(Acl &$acl) {
-		$userManager = $this->userManager;
 		$groupManager = $this->groupManager;
 		$acl->resolveRelation('participant', function ($participant) use (&$acl, &$userManager, &$groupManager) {
 			if ($acl->getType() === Acl::PERMISSION_TYPE_USER) {
-				$user = $userManager->get($participant);
-				if ($user !== null) {
-					return new User($user);
+				if ($this->userManager->userExists($acl->getParticipant())) {
+					return new User($acl->getParticipant(), $this->userManager);
 				}
 				$this->logger->debug('User ' . $acl->getId() . ' not found when mapping acl ' . $acl->getParticipant());
 				return null;
@@ -499,9 +497,8 @@ class BoardMapper extends QBMapper implements IPermissionMapper {
 	public function mapOwner(Board &$board) {
 		$userManager = $this->userManager;
 		$board->resolveRelation('owner', function ($owner) use (&$userManager) {
-			$user = $userManager->get($owner);
-			if ($user !== null) {
-				return new User($user);
+			if ($this->userManager->userExists($owner)) {
+				return new User($owner, $userManager);
 			}
 			return null;
 		});
diff --git a/lib/Db/CardMapper.php b/lib/Db/CardMapper.php
index d1b70c600..0b5170a54 100644
--- a/lib/Db/CardMapper.php
+++ b/lib/Db/CardMapper.php
@@ -607,9 +607,8 @@ class CardMapper extends QBMapper implements IPermissionMapper {
 	public function mapOwner(Card &$card) {
 		$userManager = $this->userManager;
 		$card->resolveRelation('owner', function ($owner) use (&$userManager) {
-			$user = $userManager->get($owner);
-			if ($user !== null) {
-				return new User($user);
+			if ($userManager->userExists($owner)) {
+				return new User($owner, $this->userManager);
 			}
 			return null;
 		});
diff --git a/lib/Db/RelationalObject.php b/lib/Db/RelationalObject.php
index bd176e1b8..1928db097 100644
--- a/lib/Db/RelationalObject.php
+++ b/lib/Db/RelationalObject.php
@@ -33,7 +33,7 @@ class RelationalObject implements JsonSerializable {
 	 * RelationalObject constructor.
 	 *
 	 * @param $primaryKey string
-	 * @param $object
+	 * @param callable|mixed $object
 	 */
 	public function __construct($primaryKey, $object) {
 		$this->primaryKey = $primaryKey;
@@ -47,16 +47,24 @@ class RelationalObject implements JsonSerializable {
 		);
 	}
 
+	public function getObject() {
+		if (is_callable($this->object)) {
+			$this->object = call_user_func($this->object, $this);
+		}
+
+		return $this->object;
+	}
+
 	/**
 	 * This method should be overwritten if object doesn't implement \JsonSerializable
 	 *
 	 * @throws \Exception
 	 */
 	public function getObjectSerialization() {
-		if ($this->object instanceof JsonSerializable) {
-			return $this->object->jsonSerialize();
+		if ($this->getObject() instanceof JsonSerializable) {
+			return $this->getObject()->jsonSerialize();
 		} else {
-			throw new \Exception('jsonSerialize is not implemented on ' . get_class($this));
+			throw new \Exception('jsonSerialize is not implemented on ' . get_class($this->getObject()));
 		}
 	}
 
diff --git a/lib/Db/User.php b/lib/Db/User.php
index d595ece75..c9750508d 100644
--- a/lib/Db/User.php
+++ b/lib/Db/User.php
@@ -24,26 +24,31 @@
 namespace OCA\Deck\Db;
 
 use OCP\IUser;
+use OCP\IUserManager;
 
 class User extends RelationalObject {
-	public function __construct(IUser $user) {
-		$primaryKey = $user->getUID();
-		parent::__construct($primaryKey, $user);
+
+	private IUserManager $userManager;
+	public function __construct($uid, IUserManager $userManager) {
+		$this->userManager = $userManager;
+		parent::__construct($uid, function ($object) {
+			return $this->userManager->get($object->getPrimaryKey());
+		});
 	}
 
 	public function getObjectSerialization() {
 		return [
-			'uid' => $this->object->getUID(),
-			'displayname' => $this->object->getDisplayName(),
-			'type' => 0
+			'uid' => $this->getObject()->getUID(),
+			'displayname' => $this->getObject()->getDisplayName(),
+			'type' => Acl::PERMISSION_TYPE_USER
 		];
 	}
 
 	public function getUID() {
-		return $this->object->getUID();
+		return $this->getPrimaryKey();
 	}
 
 	public function getDisplayName() {
-		return $this->object->getDisplayName();
+		return $this->userManager->getDisplayName($this->getPrimaryKey());
 	}
 }
diff --git a/lib/Service/CardService.php b/lib/Service/CardService.php
index 869022dcd..196e12859 100644
--- a/lib/Service/CardService.php
+++ b/lib/Service/CardService.php
@@ -119,7 +119,7 @@ class CardService {
 	public function enrichCards($cards) {
 		$user = $this->userManager->get($this->currentUser);
 
-		$cardIds = array_map(function (Card $card) {
+		$cardIds = array_map(function (Card $card) use ($user) {
 			// Everything done in here might be heavy as it is executed for every card
 			$cardId = $card->getId();
 			$this->cardMapper->mapOwner($card);
diff --git a/lib/Service/PermissionService.php b/lib/Service/PermissionService.php
index d0630a633..c3bb6c133 100644
--- a/lib/Service/PermissionService.php
+++ b/lib/Service/PermissionService.php
@@ -260,22 +260,20 @@ class PermissionService {
 		}
 
 		$users = [];
-		$owner = $this->userManager->get($board->getOwner());
-		if ($owner === null) {
+		if (!$this->userManager->userExists($board->getOwner())) {
 			$this->logger->info('No owner found for board ' . $board->getId());
 		} else {
-			$users[$owner->getUID()] = new User($owner);
+			$users[$board->getOwner()] = new User($board->getOwner(), $this->userManager);
 		}
 		$acls = $this->aclMapper->findAll($boardId);
 		/** @var Acl $acl */
 		foreach ($acls as $acl) {
 			if ($acl->getType() === Acl::PERMISSION_TYPE_USER) {
-				$user = $this->userManager->get($acl->getParticipant());
-				if ($user === null) {
+				if (!$this->userManager->userExists($acl->getParticipant())) {
 					$this->logger->info('No user found for acl rule ' . $acl->getId());
 					continue;
 				}
-				$users[$user->getUID()] = new User($user);
+				$users[$acl->getParticipant()] = new User($acl->getParticipant(), $this->userManager);
 			}
 			if ($acl->getType() === Acl::PERMISSION_TYPE_GROUP) {
 				$group = $this->groupManager->get($acl->getParticipant());
@@ -284,7 +282,7 @@ class PermissionService {
 					continue;
 				}
 				foreach ($group->getUsers() as $user) {
-					$users[$user->getUID()] = new User($user);
+					$users[$user->getUID()] = new User($user->getUID(), $this->userManager);
 				}
 			}
 
@@ -305,7 +303,7 @@ class PermissionService {
 						if ($user === null) {
 							$this->logger->info('No user found for circle member ' . $member->getUserId());
 						} else {
-							$users[$member->getUserId()] = new User($user);
+							$users[$member->getUserId()] = new User($member->getUserId(), $this->userManager);
 						}
 					}
 				} catch (\Exception $e) {