hi, what's the recommended design for avoiding fields of DTOs in the value stack being updated through (HTML) DOM manipulation?
consider a typical edit page containing a form with some fields. this page is a visual representation of a DTO we are about to update. the DTO is set in the action - it was fetched from the database during prepare() - and therefore is accessible from the value stack (the JSP generating the edit page populated the form fields with corresponding DTO fields using OGNL). by manipulating the DOM of the edit page (e.g. using Firebug) one can add a new input field to the form. this input field may correspond to a DTO read-only instance variable we would like the action *not* to update. upon form submission, the DTO is updated with all the form fields (existing ones + the one added to the DOM) and persisted in the database. there are several possible solutions to this issue: solution 1: validate the DTO before persisting it in the database. the DTO would be persisted only if no "read-only" fields were updated. this could be achieved e.g. through a comparison between the updated DTO and a clone of the original DTO (fetched during prepare()). solution 2: another way to solve this would be to apply authorisation rules in the model and therefore guarantee that certain DTO setters are "read-only". solution 3: use a DTO proxy object instead of the DTO itself. the DTO proxy object would contain the DTO read-write fields only. the DTO would then be updated with the corresponding DTO proxy fields before being persisted in the database. solution 4: not to use the "model-driven" approach and have setters in the action corresponding to DTO read-write fields. the DTO would then be updated with the corresponding action fields before being persisted in the database. i am not considering a solution where setters of "read-only" fields are removed from the DTO class as this would invalidate the update of those fields by anyone (which includes users with higher privileges). i would like to hear about your design solutions to this issue. thanks in advance, santos.
