[Springframework-developer] MVC Forms

[Ken K. <kk...@kk...>]

Juergen,

There is a problem in my version 1 prototype of the petclinic demo.

Should a user change an owner's info and then use the Back button and 
try and resubmit the form (which has sessionForm==true) to make another 
change, the method AbstractFormController.handleRequestInternal will 
call userObject to retrieve the form object from the session. Since the 
form object is no longer there, this results in a ServletException. My 
current working version works around this by overriding isFormSubmission 
which only returns true if the method was POST and it can find the form 
object. Since I have also overriden formBackingObject to provide the 
owner info in the first place, this results in a redisplay of the form 
with the user's latest changes silently ignored. This process must seem 
unreasonable to users who know nothing about the problems enterprise 
application developers face with the browser's Back button. Maybe I'm 
going about this wrong.

This also brings up the issue of when a developer specifically wants to 
forbid resubmission as in a purchase transaction. Struts provides 
support for a synchronizing token to prevent duplicate submissions using 
the <html:form> tag.

Perhaps we should provide some infrastructure to help developers solve 
these problems in a consistent way.

I am also a little bit concerned over the process used in 
AbstractFormController and SimpleFormController. Developers may see this 
as too restrictive, especially if they are used to the flexible 
forwarding strategy of Struts.

What are your thoughts on this ?

Ken