The details of the actual goal are sketchy, but if the ActionForm is polymorphic, you can add a new ActionForm type without touching the Action.
The Action would just need to know to expect this super class, and hand this parameter to that method. In general, the less one object knows about the specific type of another, the better ;-) Justin Piper wrote: > > Maybe I'm misinterpreting your suggestion, but wouldn't this be putting > logic in your ActionForm that should be in the ActionServlet? What about > defining several additional perform methods in your ActionServlet that > handle specific superclasses of ActionForm, and an abstract method > visit(YourActionServlet caller, ActionMapping mapping, ServletRequest > request, ServletResponse response) to the ActionList. The concrete visit() > methods in all your derived classes would just call caller.perform(), > passing itself as the ActionForm parameter. > > -----Original Message----- > From: Ted Husted [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, October 23, 2001 6:08 PM > To: [EMAIL PROTECTED] > Subject: Re: What is proper way to determine ActionForm type? > > I'd consider using some type of polymorphism, where all of these > ActionForms share a common ancestor, with a known method, like > addItem(object), that would act as a wrapper. Each ActionForm could then > override addItem to call whatever list is appropriate. > > ProductList extends ActionList > addItem(addProductItem(o)) ; > AddressList extends ActionList > addItem(addAddressItem(o)); > > In your framework Action, you could then just cast as the ancestor > method and call the overridden method > > ActionList actionList = (ActionList) form; > > actionList.addItem(o); > > If you are still interested in determining the ActionForm bean type, see > the source of the processActionForm method for how the ActionServlet > does it. > > If you need to call a method based on a parameter, see the source for > DispatchAction in the Actions package, which calls a local method based > on the string given as the parameter property. > > -- Ted Husted, Husted dot Com, Fairport NY USA. > -- Custom Software ~ Technical Services. > -- Tel +1 716 737-3463 > -- http://www.husted.com/struts/ > > Stephen Hood wrote: > > > > I am trying to write a generic Action class that I can use with any > > ActionForm to add an item to any collection property it may contain. For > > example, if I had two ActionForms which each contain a collection (say > > "AddressList" and "ProductList"), I could call the same Action with either > > form, pass it the name of the collection, and have it add a new item to > it, > > passing control back to the calling View. > > > > In order to make it generic, I want the class to figure out the ActionForm > > type specified in the mapping, recast the generic ActionForm as the proper > > type, and then add another item to the collection indicated by a passed > > request attribute. > > > > To dynamically determine the ActionForm type, I'm trying to use the > > equivalent of ActionMapping.getFormClass(), which has been deprecated. > The > > suggested alternative is to use ActionMapping.getName() and then use it to > > look-up the ActionFormBean. It seems the way to do this is to use > > ActionFormBeans.findFormBean(String beanName). However, the following > code > > returns a null ActionFormBean. > > > > String formBeanName = mapping.getName(); > > ActionFormBeans actionFormBeans = new ActionFormBeans(); > > ActionFormBean theFormBean = actionFormBeans.findFormBean(formBeanName); > > > > I assume that my ActionFormBeans object itself is empty and I am not > > creating or populating it properly, but I could not find details in the > > Struts javadoc. > > > > Is this the correct approach? > > > > thanks for any suggestions, > > --Steve -- Ted Husted, Husted dot Com, Fairport NY USA. -- Custom Software ~ Technical Services. -- Tel +1 716 737-3463 -- http://www.husted.com/struts/
