Fixed #3410

CHANGELOG-v3.md

@@ -12,6 +12,7 @@
 - Fixed a bug where the `ContentBehaviour` and `ElementQueryBehavior` classes could be missing some field properties. ([#3400](https://github.com/craftcms/cms/issues/3400))
 - Fixed a bug where some fields within Matrix fields could lose their values after enabling the “Manage blocks on a per-site basis” setting. ([verbb/super-table/203](https://github.com/verbb/super-table/issues/203))
 - Fixed a bug where HTML Purifier wasn’t being initialized with HTML 5 element support.
+- Fixed a bug where it was possible to save Assets fields with the “Restrict allowed file types?” setting enabled, but no specific file types selected. ([#3410](https://github.com/craftcms/cms/issues/3410))
 
 ## 3.0.28 - 2018-10-23
 

src/fields/Assets.php

@@ -121,6 +121,20 @@ public function init()
         $this->inputJsClass = 'Craft.AssetSelectInput';
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function rules()
+    {
+        $rules = parent::rules();
+
+        $rules[] = [['allowedKinds'], 'required', 'when' => function(self $field): bool {
+            return (bool)$field->restrictFiles;
+        }];
+
+        return $rules;
+    }
+
     /**
      * @inheritdoc
      */

src/templates/_components/fieldtypes/Assets/settings.html

@@ -92,6 +92,7 @@
                     checked: (option.value in field.allowedKinds)
                 }) }}
             {% endfor %}
+            {{ forms.errorList(field.getErrors('allowedKinds')) }}
         </div>
     {% endblock %}