added __hash__ methods

openlp/core/lib/serviceitem.py

@@ -485,6 +485,12 @@ class ServiceItem(object):
         """
         return self.unique_identifier != other.unique_identifier
 
+    def __hash__(self):
+        """
+        Return the hash for the service item.
+        """
+        return self.unique_identifier
+
     def is_media(self):
         """
         Confirms if the ServiceItem is media

openlp/plugins/custom/lib/db.py

@@ -41,14 +41,19 @@ class CustomSlide(BaseModel):
     """
     CustomSlide model
     """
-    # By default sort the customs by its title considering language specific
-    # characters.
+    # By default sort the customs by its title considering language specific characters.
     def __lt__(self, other):
         return get_locale_key(self.title) < get_locale_key(other.title)
 
     def __eq__(self, other):
         return get_locale_key(self.title) == get_locale_key(other.title)
 
+    def __hash__(self):
+        """
+        Return the hash for a custom slide.
+        """
+        return self.id
+
 
 def init_schema(url):
     """