In py4web, when form validation fails on a datetime field, py4web throws and exception.
In the IS_DATETIME validator, when validation fails, validate() returns value as string (the original value).
The form code tries to display the fields properly by calling field's validator formatter().
Since the value is string and not datetime, formatter() throws exception.
but now I'm not sure whether change should be pydal or py4web.
Should the formatter() handle value with type of string?
Or, should form not try to call formatter() when there is an error?