Struts appears to be ignoring the ActionForms that I am trying to manually put in the session. If the ActionForm is not the same class type as what is defined in struts-config.xml then Struts ignores it and creates a new one when the page is processed. Is this the intended behavior? If so, I would like to propose a slight change to the logic Struts uses when creating an instance of an action form. Currently, as I understand it, Struts will check to see if an instance of the ActionForm exists in the session based on the name assigned to the attribute and the class type of the attribute. If either do not match, then Struts creates a new ActionForm of the type defined in the mapping. What about changing this so that the object in the session can be of the same type, *or* a subclass of the class specified in the struts-config.xml? Can anyone think of a scenario where this would cause problems? I am having problems with the design of my application because of this. If this functionality was supported things would become simpler and the app would be more extensible. Comments? -Bob -----Original Message----- From: Hayden,Robert IT BIP-US-R Sent: Tuesday, March 20, 2001 1:09 AM To: [EMAIL PROTECTED] Subject: Object oriented question regarding ActionForms I have an object oriented question related to how Struts instantiates an ActionForm. What I am trying to do is utilize a factory for creation of my ActionForms. In my application, I have a base (abstract) ActionForm class called Fermentation, and subclasses FermentationYeast, FermentationEcoli, etc... The factory is called from my Action servlet to create the appropriate instance of an ActionForm (a subtype of Fermentation). Then I save the newly created ActionForm in the session. The object type that gets saved in the session is the subtype, but in my Struts config I am specifying the base type. I want Struts to read this object from the session, but Struts always creates a new ActionForm of the base type. I want it to find and use the subtype! For example, the Action servlet calls the factory and the factory returns a FermentationYeast. This object is saved in the session, and then I forward to the EditFermentation page. The EditFermentation page is mapped in the Struts config to use a Fermentation form, so Struts does not recognize the FermentationYeast that is already in the session and it creates a new ActionForm. Even though a FermentationYeast *is a* Fermentation, Struts does not seem to support this. I think it would be helpful if Struts supported generalization... or if it does and I am missing something here please let me know :) Or, If you think I should change my design, please let me know this as well. I think I have a good reason to need to do this. The first page is where the user enters common information, then the next page is loaded based on the type of the Fermentation (ActionFrom). I could create 2 separate ActionForms (one for the common attributes and then another for the details) but I would like to use inheritance to model this relationship. In other words, I want to create a single ActionForm which will be used across multiple pages, but I want to share pages that ask for the same information. Thanks, Bob
