return item id, exclude empty annotations

pandora/annotation/models.py

@@ -237,6 +237,8 @@ class Annotation(models.Model):
 
         if layer or (keys and 'layer' in keys):
             j['layer'] = self.layer
+        if keys and 'item' in keys:
+            j['item'] = self.item.public_id
         if keys:
             _j = {}
             for key in keys:

pandora/annotation/views.py

@@ -58,7 +58,7 @@ def order_query(qs, sort):
         order = '%s%s' % (operator, key)
         order_by.append(order)
     if order_by:
-        qs = qs.order_by(*order_by, nulls_last=True)
+        qs = qs.order_by(*order_by, nulls_last=True).exclude(value='')
     return qs
 
 def findAnnotations(request, data):