--- Revision None
+++ Revision 633436626234
@@ -0,0 +1,29 @@
+    def update_fields(self, record_id, fields):
+        """Safely update a number of fields. 'fields' being a
+        dictionary with path_tuple: value for only the fields we want
+        to change the value of, where path_tuple is a tuple of
+        fieldnames indicating the path to the possibly nested field
+        we're interested in.
+        """
+        while True:
+            record = self.db[record_id]
+            modified = False
+            for path, value in fields.items():
+                if not isinstance(path, tuple):
+                    path = (path,)
+                parent = record
+                for field in path[:-1]:
+                    parent = parent.setdefault(field, {})
+                if parent.get(path[-1]) == value:
+                    continue
+                modified = True
+                parent[path[-1]] = value
+            if modified:
+                try:
+                    self.db[record.id] = record
+                except ResourceConflict:
+                    logger.debug(
+                        "Update of record with id %s in database %s failed." % (
+                            record_id, self.db.name))
+                    continue
+            break