diff --git a/Models/CollectionMapper.php b/Models/CollectionMapper.php
index 36a7bbc..5e2e179 100644
--- a/Models/CollectionMapper.php
+++ b/Models/CollectionMapper.php
@@ -21,12 +21,13 @@ use phpOMS\DataStorage\Database\Query\Column;
 class CollectionMapper extends MediaMapper
 {
     protected static $hasMany = [
-        'source' => [
-            'mapper' => null,
-            'table'  => 'media_relation',
-            'dst'    => 'media_relation_dst',
-            'src'    => 'media_relation_src'
-        ]
+        'sources' => [
+            'mapper'         => '\Modules\Media\Models\MediaMapper', /* mapper of the related object */
+            'relationmapper' => null, /* if the relation itself is a more complex object that has it's own mapper */
+            'table'          => 'media_relation', /* table of the related object, null if no relation table is used (many->1) */
+            'dst'            => 'media_relation_dst',
+            'src'            => 'media_relation_src',
+        ],
     ];
 
     /**
diff --git a/Models/MediaMapper.php b/Models/MediaMapper.php
index f45d99f..c390f8e 100644
--- a/Models/MediaMapper.php
+++ b/Models/MediaMapper.php
@@ -34,7 +34,7 @@ class MediaMapper extends DataMapperAbstract
         'media_versioned'  => ['name' => 'media_versioned', 'type' => 'bool', 'internal' => 'versioned'],
         'media_file'       => ['name' => 'media_file', 'type' => 'string', 'internal' => 'path'],
         'media_extension'  => ['name' => 'media_extension', 'type' => 'string', 'internal' => 'extension'],
-        'media_collection' => ['name' => 'media_collection', 'type' => 'int', 'internal' => 'collection'],
+        'media_collection' => ['name' => 'media_collection', 'type' => 'bool', 'internal' => 'collection'],
         'media_size'       => ['name' => 'media_size', 'type' => 'int', 'internal' => 'size'],
         'media_created_by' => ['name' => 'media_created_by', 'type' => 'int', 'internal' => 'createdBy'],
         'media_created_at' => ['name' => 'media_created_at', 'type' => 'DateTime', 'internal' => 'createdAt'],