Avoid useless dictionary computation in render_dict

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41173 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/Formulator/Widget.py

@@ -1331,6 +1331,8 @@ class DateTimeWidget(Widget):
                 format of provided value.
         query : Passthrough of given value.
     """
+    if not value:
+      return None
     format_dict = self.format_to_sql_format_dict
     input_order = format_dict.get(self.getInputOrder(field),
                                   self.sql_format_default)
@@ -1807,6 +1809,8 @@ class FloatWidget(TextWidget):
                 format of provided value.
         query : Passthrough of given value.
     """
+    if not value:
+      return None
     precision = field.get_value('precision')
     format = '0'
     if precision: