diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index a097f0c..6d03fc9 100644
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -149,7 +149,7 @@ final class ApiController extends Controller
         $mediaCreated = [];
 
         foreach ($status as $uFile) {
-            if (!is_null($created = self::createDbEntry($uFile, $account))) {
+            if (($created = self::createDbEntry($uFile, $account)) !== null) {
                 $mediaCreated[] = $created;
             }
         }
diff --git a/Models/Collection.php b/Models/Collection.php
index f23cbfd..d24e426 100644
--- a/Models/Collection.php
+++ b/Models/Collection.php
@@ -33,19 +33,21 @@ class Collection extends Media implements \Iterator
      */
     private $sources = [];
 
+    /**
+     * Extension name.
+     *
+     * @var string
+     * @since 1.0.0
+     */
     protected $extension = 'collection';
 
-    protected $versioned = false;
-
     /**
-     * Constructor.
+     * Versioned.
      *
-     * @since  1.0.0
+     * @var bool
+     * @since 1.0.0
      */
-    public function __construct()
-    {
-        parent::__construct();
-    }
+    protected $versioned = false;
 
     /**
      * Set sources.
@@ -87,36 +89,57 @@ class Collection extends Media implements \Iterator
         return $this->sources;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function setExtension(string $extension) : void
     {
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function setVersioned(bool $versioned) : void
     {
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function rewind() : void
     {
-        reset($this->sources);
+        \reset($this->sources);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function current()
     {
-        return current($this->sources);
+        return \current($this->sources);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function key()
     {
-        return key($this->sources);
+        return \key($this->sources);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function next() : void
     {
-        next($this->sources);
+        \next($this->sources);
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function valid()
     {
-        return current($this->sources) !== false;
+        return \current($this->sources) !== false;
     }
 }
diff --git a/Models/CollectionMapper.php b/Models/CollectionMapper.php
index dfe187b..85febac 100644
--- a/Models/CollectionMapper.php
+++ b/Models/CollectionMapper.php
@@ -16,7 +16,12 @@ namespace Modules\Media\Models;
 
 
 final class CollectionMapper extends MediaMapper
-{
+{    /**
+     * Has many relation.
+     *
+     * @var array<string, array<string, string>>
+     * @since 1.0.0
+     */
     protected static $hasMany = [
         'sources' => [
             'mapper' => MediaMapper::class, /* mapper of the related object */
diff --git a/Models/Media.php b/Models/Media.php
index ba2124c..de8942f 100644
--- a/Models/Media.php
+++ b/Models/Media.php
@@ -141,13 +141,13 @@ class Media implements \JsonSerializable
      *
      * @since  1.0.0
      */
-    public function setAbsolute(bool $absolute) : void /* void */
+    public function setAbsolute(bool $absolute) : void
     {
         $this->isAbsolute = $absolute;
     }
 
     /**
-     * @return mixed
+     * @return int|\phpOMS\Account\Account
      *
      * @since  1.0.0
      */
@@ -335,7 +335,7 @@ class Media implements \JsonSerializable
     /**
      * {@inheritdoc}
      */
-    public function toArray()
+    public function toArray() : array
     {
         return [
             'id'          => $this->id,
diff --git a/Models/MediaMapper.php b/Models/MediaMapper.php
index 61fb37e..7951237 100644
--- a/Models/MediaMapper.php
+++ b/Models/MediaMapper.php
@@ -4,7 +4,7 @@
  *
  * PHP Version 7.2
  *
- * @package    TBD
+ * @package    Modules\Media\Models
  * @copyright  Dennis Eichhorn
  * @license    OMS License 1.0
  * @version    1.0.0
@@ -17,6 +17,14 @@ namespace Modules\Media\Models;
 use Modules\Admin\Models\AccountMapper;
 use phpOMS\DataStorage\Database\DataMapperAbstract;
 
+/**
+ * Media mapper class.
+ *
+ * @package    Modules\Media\Models
+ * @license    OMS License 1.0
+ * @link       http://website.orange-management.de
+ * @since      1.0.0
+ */
 class MediaMapper extends DataMapperAbstract
 {
 
@@ -41,6 +49,12 @@ class MediaMapper extends DataMapperAbstract
         'media_created_at'      => ['name' => 'media_created_at', 'type' => 'DateTime', 'internal' => 'createdAt'],
     ];
 
+    /**
+     * Belongs to.
+     *
+     * @var array<string, array<string, string>>
+     * @since 1.0.0
+     */
     protected static $belongsTo = [
         'createdBy' => [
             'mapper' => AccountMapper::class,
diff --git a/Models/UploadFile.php b/Models/UploadFile.php
index 387008e..2f325c5 100644
--- a/Models/UploadFile.php
+++ b/Models/UploadFile.php
@@ -28,7 +28,13 @@ use phpOMS\System\File\Local\Directory;
  */
 class UploadFile
 {
-    public const PATH_GENERATION_LIMIT = 1000;
+    /**
+     * Limit of iterations to find a possible random path for the file to upload to.
+     *
+     * @var int
+     * @since 1.0.0
+     */
+    private const PATH_GENERATION_LIMIT = 1000;
 
     /**
      * Image interlaced.
diff --git a/Theme/Backend/media-single.tpl.php b/Theme/Backend/media-single.tpl.php
index 54a405f..137ce4e 100644
--- a/Theme/Backend/media-single.tpl.php
+++ b/Theme/Backend/media-single.tpl.php
@@ -61,7 +61,7 @@ echo $this->getData('nav')->render();
                     <td><?= $this->getHtml('Created') ?>
                 <tbody>
                     <?php
-                        if (!is_dir($media->isAbsolute() ? $path : __DIR__ . '/../../../' . \ltrim($media->getPath(), '//'))
+                        if (!\is_dir($media->isAbsolute() ? $path : __DIR__ . '/../../../' . \ltrim($media->getPath(), '//'))
                             || $media->getPath() === ''
                         ) :
                             foreach ($media as $key => $value) :
@@ -78,12 +78,12 @@ echo $this->getData('nav')->render();
                     <?php endforeach; else : $path = $this->dirPathFunction($media, $this->request->getData('sub') ?? ''); ?>
                         <?php $list = \phpOMS\System\File\Local\Directory::list($path);
                             foreach ($list as $key => $value) :
-                                $url = UriFactory::build('/{/lang}/backend/media/single?{?}&id=' . $media->getId() . '&sub=' . substr($value, strlen($media->getPath())));
-                                $icon = $this->fileIconFunction(FileUtils::getExtensionType(!is_dir($value) ? File::extension($value) : 'collection'));
+                                $url = UriFactory::build('/{/lang}/backend/media/single?{?}&id=' . $media->getId() . '&sub=' . \substr($value, \strlen($media->getPath())));
+                                $icon = $this->fileIconFunction(FileUtils::getExtensionType(!\is_dir($value) ? File::extension($value) : 'collection'));
                         ?>
                         <tr data-href="<?= $url; ?>">
                             <td><a href="<?= $url; ?>"><i class="fa fa-<?= $this->printHtml($icon); ?>"></i></a>
-                            <td><a href="<?= $url; ?>"><?= substr($value, strlen($media->getPath())); ?></a>
+                            <td><a href="<?= $url; ?>"><?= \substr($value, \strlen($media->getPath())); ?></a>
                             <td><a href="<?= $url; ?>"><?= !\is_dir($value) ? File::extension($value) : 'collection'; ?></a>
                             <td><a href="<?= $url; ?>"><?= !\is_dir($value) ? File::size($value) : ''; ?></a>
                             <td><a href="<?= $url; ?>"><?= File::owner($value); ?></a>
diff --git a/Views/MediaView.php b/Views/MediaView.php
index 6a36ec1..dc80d69 100644
--- a/Views/MediaView.php
+++ b/Views/MediaView.php
@@ -36,7 +36,7 @@ class MediaView extends View
     {
         if (is_file($media->getPath() . $sub)
             && StringUtils::startsWith(
-                \str_replace('\\', '/', realpath($media->getPath() . $sub)),
+                \str_replace('\\', '/', \realpath($media->getPath() . $sub)),
                 $media->getPath()
             )
         ) {
@@ -48,9 +48,9 @@ class MediaView extends View
 
     protected function dirPathFunction(Media $media, string $sub) : string
     {
-        if (is_dir($media->getPath() . $sub)
+        if (\is_dir($media->getPath() . $sub)
             && StringUtils::startsWith(
-                \str_replace('\\', '/', realpath($media->getPath() . $sub)),
+                \str_replace('\\', '/', \realpath($media->getPath() . $sub)),
                 $media->getPath()
             )
         ) {
@@ -63,8 +63,8 @@ class MediaView extends View
     protected function isCollectionFunction(Media $media, string $sub) : bool
     {
         return ($media->getExtension() === 'collection'
-                && !is_file($media->getPath() . $sub))
-            || (is_dir($media->getPath())
+                && !\is_file($media->getPath() . $sub))
+            || (\is_dir($media->getPath())
                 && ($sub === null || \is_dir($media->getPath() . $sub))
         );
     }