avoid ['']

oml/item/api.py

@@ -251,7 +251,7 @@ def findMetadata(data):
                 j = items[m.data_hash]
                 for key in [k['id'] for k in settings.config['itemKeys'] if isinstance(k['type'], list)]:
                     if key in j and not isinstance(j[key], list):
-                        j[key] = [j[key]]
+                        j[key] = [j[key]] if j[key] else []
             else:
                 items[m.data_hash]['users'].append(m.user_id)
             response['items'] = list(items.values())
@@ -279,7 +279,7 @@ def getMetadata(data):
         response.update(models.Metadata.load(key, value))
     for key in [k['id'] for k in settings.config['itemKeys'] if isinstance(k['type'], list)]:
         if key in response and not isinstance(response[key], list):
-            response[key] = [response[key]]
+            response[key] = [response[key]] if response[key] else []
     return response
 actions.register(getMetadata)
 

oml/media/__init__.py

@@ -16,6 +16,7 @@ from . import txt
 from . import opf
 
 from meta.utils import decode_html_data, to_isbn13
+import settings
 
 def get_id(f=None, data=None):
     if data:
@@ -106,5 +107,11 @@ def metadata(f, from_=None):
         if not data['title'].strip():
             del data['title']
     data = decode_html_data(data)
+    for key in list(data):
+        if not data[key]:
+            del data[key]
+    for key in [k['id'] for k in settings.config['itemKeys'] if isinstance(k['type'], list)]:
+        if key in data and not isinstance(data[key], list):
+            data[key] = [data[key]] if data[key] else []
     return data