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
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