diff --git a/application/controllers/ApiV1ContactgroupsController.php b/application/controllers/ApiV1ContactgroupsController.php
index 31650a960..505a361de 100644
--- a/application/controllers/ApiV1ContactgroupsController.php
+++ b/application/controllers/ApiV1ContactgroupsController.php
@@ -17,6 +17,7 @@
 use ipl\Web\Filter\QueryString;
 use ipl\Web\Url;
 use Ramsey\Uuid\Uuid;
+use stdClass;
 
 class ApiV1ContactgroupsController extends CompatController
 {
@@ -44,6 +45,8 @@ public function indexAction(): void
         $results = [];
         $responseCode = 200;
         $db = Database::get();
+
+        /** @var ?string $identifier */
         $identifier = $request->getParam('identifier');
 
         if ($identifier && ! Uuid::isValid($identifier)) {
@@ -87,6 +90,8 @@ function (Filter\Condition $condition) {
 
                 if ($identifier !== null) {
                     $stmt->where(['external_uuid = ?' => $identifier]);
+
+                    /** @var stdClass|false $result */
                     $result = $db->fetchOne($stmt);
 
                     if ($result === false) {
@@ -123,6 +128,7 @@ function (Filter\Condition $condition) {
 
                 $res = $db->select($stmt->offset($offset));
                 do {
+                    /** @var stdClass $row */
                     foreach ($res as $i => $row) {
                         $users = $this->fetchUserIdentifiers($row->contactgroup_id);
                         if ($users) {
@@ -150,9 +156,7 @@ function (Filter\Condition $condition) {
                     $this->httpBadRequest('Cannot filter on POST');
                 }
 
-                $data = $request->getPost();
-
-                $this->assertValidData($data);
+                $data = $this->getValidatedData();
 
                 $db->beginTransaction();
 
@@ -187,9 +191,7 @@ function (Filter\Condition $condition) {
                     $this->httpBadRequest('Identifier is required');
                 }
 
-                $data = $request->getPost();
-
-                $this->assertValidData($data);
+                $data = $this->getValidatedData();
 
                 if ($identifier !== $data['id']) {
                     $this->httpBadRequest('Identifier mismatch');
@@ -278,6 +280,7 @@ private function fetchUserIdentifiers(int $contactgroupId): ?array
      */
     private function getUserId(string $identifier): int
     {
+        /** @var stdClass|false $user */
         $user = Database::get()->fetchOne(
             (new Select())
                 ->from('contact')
@@ -301,6 +304,7 @@ private function getUserId(string $identifier): int
      */
     private function getContactgroupId(string $identifier): ?int
     {
+        /** @var stdClass|false $contactgroup */
         $contactgroup =  Database::get()->fetchOne(
             (new Select())
                 ->from('contactgroup')
@@ -314,7 +318,11 @@ private function getContactgroupId(string $identifier): ?int
     /**
      * Add a new contactgroup with the given data
      *
-     * @param array<string, mixed> $data
+     * @param array{
+     *        id: string,
+     *        name: string,
+     *        users?: string[],
+     *    } $data
      */
     private function addContactgroup(array $data): void
     {
@@ -364,12 +372,17 @@ private function removeContactgroup(int $id): void
     /**
      * Assert that the given data contains the required fields
      *
-     * @param array<string, mixed> $data
+     * @return array{
+     *       id: string,
+     *       name: string,
+     *       users?: string[],
+     *   }
      *
      * @throws HttpBadRequestException
      */
-    private function assertValidData(array $data): void
+    private function getValidatedData(): array
     {
+        $data = $this->getRequest()->getPost();
         $msgPrefix = 'Invalid request body: ';
 
         if (! isset($data['id'], $data['name'])
@@ -398,5 +411,12 @@ private function assertValidData(array $data): void
                 //TODO: check if users exist, here?
             }
         }
+
+        /** @var array{
+         * id: string,
+         * name: string,
+         * users?: string[],
+         * } $data */
+        return $data;
     }
 }
diff --git a/application/controllers/ApiV1ContactsController.php b/application/controllers/ApiV1ContactsController.php
index 117dffcfb..32d25e7d0 100644
--- a/application/controllers/ApiV1ContactsController.php
+++ b/application/controllers/ApiV1ContactsController.php
@@ -18,6 +18,7 @@
 use ipl\Web\Filter\QueryString;
 use ipl\Web\Url;
 use Ramsey\Uuid\Uuid;
+use stdClass;
 
 class ApiV1ContactsController extends CompatController
 {
@@ -44,6 +45,8 @@ public function indexAction(): void
         $results = [];
         $responseCode = 200;
         $db = Database::get();
+
+        /** @var ?string $identifier */
         $identifier = $request->getParam('identifier');
 
         if ($identifier && ! Uuid::isValid($identifier)) {
@@ -91,6 +94,8 @@ function (Filter\Condition $condition) {
 
                 if ($identifier !== null) {
                     $stmt->where(['external_uuid = ?' => $identifier]);
+
+                    /** @var stdClass|false $result */
                     $result = $db->fetchOne($stmt);
 
                     if ($result === false) {
@@ -136,6 +141,7 @@ function (Filter\Condition $condition) {
 
                 $res = $db->select($stmt->offset($offset));
                 do {
+                    /** @var stdClass $row */
                     foreach ($res as $i => $row) {
                         if ($row->username === null) {
                             unset($row->username);
@@ -172,9 +178,7 @@ function (Filter\Condition $condition) {
                     $this->httpBadRequest('Cannot filter on POST');
                 }
 
-                $data = $request->getPost();
-
-                $this->assertValidData($data);
+                $data = $this->getValidatedData();
 
                 $db->beginTransaction();
 
@@ -209,9 +213,7 @@ function (Filter\Condition $condition) {
                     $this->httpBadRequest('Identifier is required');
                 }
 
-                $data = $request->getPost();
-
-                $this->assertValidData($data);
+                $data = $this->getValidatedData();
 
                 if ($identifier !== $data['id']) {
                     $this->httpBadRequest('Identifier mismatch');
@@ -295,6 +297,7 @@ function (Filter\Condition $condition) {
      */
     private function getChannelId(string $channelName): int
     {
+        /** @var stdClass|false $channel */
         $channel = Database::get()->fetchOne(
             (new Select())
                 ->from('channel')
@@ -318,6 +321,7 @@ private function getChannelId(string $channelName): int
      */
     private function fetchContactAddresses(int $contactId): ?string
     {
+        /** @var array<string, string> $addresses */
         $addresses = Database::get()->fetchPairs(
             (new Select())
                 ->from('contact_address')
@@ -325,7 +329,11 @@ private function fetchContactAddresses(int $contactId): ?string
                 ->where(['contact_id = ?' => $contactId])
         );
 
-        return ! empty($addresses) ? json_encode($addresses) : null;
+        if (! empty($addresses)) {
+            return json_encode($addresses) ?: null;
+        }
+
+        return null;
     }
 
     /**
@@ -360,6 +368,7 @@ private function fetchGroupIdentifiers(int $contactId): ?array
      */
     private function getGroupId(string $identifier): int
     {
+        /** @var stdClass|false $group */
         $group = Database::get()->fetchOne(
             (new Select())
                 ->from('contactgroup')
@@ -383,6 +392,7 @@ private function getGroupId(string $identifier): int
      */
     protected function getContactId(string $identifier): ?int
     {
+        /** @var stdClass|false $contact */
         $contact =  Database::get()->fetchOne(
             (new Select())
                 ->from('contact')
@@ -396,7 +406,14 @@ protected function getContactId(string $identifier): ?int
     /**
      * Add a new contact with the given data
      *
-     * @param array<string, mixed> $data
+     * @param array{
+     *       id: string,
+     *       full_name: string,
+     *       default_channel: string,
+     *       username?: string,
+     *       groups?: string[],
+     *       addresses?: array<string, string>
+     *   } $data
      *
      * @return void
      */
@@ -438,7 +455,7 @@ private function assertUniqueUsername(string $username): void
         $user = Database::get()->fetchOne(
             (new Select())
                 ->from('contact')
-                ->columns(1)
+                ->columns('1')
                 ->where(['username = ?' => $username])
         );
 
@@ -503,14 +520,20 @@ private function removeContact(int $id): void
     /**
      * Assert that the given data contains the required fields
      *
-     * @param array<string, mixed> $data
-     *
-     * @return void
+     * @return array{
+     *      id: string,
+     *      full_name: string,
+     *      default_channel: string,
+     *      username?: string,
+     *      groups?: string[],
+     *      addresses?: array<string,string>
+     *  }
      *
      * @throws HttpBadRequestException
      */
-    private function assertValidData(array $data): void
+    private function getValidatedData(): array
     {
+        $data = $this->getRequest()->getPost();
         $msgPrefix = 'Invalid request body: ';
 
         if (! isset($data['id'], $data['full_name'], $data['default_channel'])
@@ -574,5 +597,16 @@ private function assertValidData(array $data): void
                 $this->httpBadRequest($msgPrefix . 'an invalid email address given');
             }
         }
+
+        /** @var array{
+         *      id: string,
+         *      full_name: string,
+         *      default_channel: string,
+         *      username?: string,
+         *      groups?: string[],
+         *      addresses?: array<string,string>
+         *  } $data
+         */
+        return $data;
     }
 }