Hi Pierre,
See intermixed below.
On Tue, 23 Jul 2002, Pierre Delisle wrote:
> Date: Tue, 23 Jul 2002 23:26:09 -0700
> From: Pierre Delisle <[EMAIL PROTECTED]>
> Reply-To: Struts Developers List <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
> Subject: action calling another action
>
> I have a 1.0 struts-based web application where a "higher-level" action
> depends on the processing associated with another lower-level action.
>
Welcome to the eternal debate over whether action chaining/nesting is a
good design pattern or not :-). I'm *not* a believer, but lets address
your questions anyway.
> For example, action "foo" needs to invoke the processing
> associated with action "bar".
>
> Using struts 1.0, I could do the following in the FooAction:
>
> ActionServletMine actionServlet =
> (ActionServletMine)mapping.getMappings().getServlet();
> ActionMapping targetMapping = actionServlet.findMapping("/bar.do");
> ((BarAction)actionServlet.getActionInstance(
> targetMapping)).perform(targetMapping, form, request, response);
>
You should have been able to pass "/bar" as the argument to the
findMapping() method, even in Struts 1.0.
> ActionServletMine is my own subclass of ActionServlet. It simply provides
> the extra method "getActionInstance()" to allow me to get access to the
> action instance associated with "targetMapping". (it calls
> processActionCreate()).
>
> Migrating to struts 1.1, I was hoping for backwards compatibility,
> but ActionMapping.getMappings() seems to have been removed without
> being first deprecated. Any reason, or am I missing something?
> (btw, I know I could simply call getServlet() within the Action subclass,
> but I'm still curious as to why getMappings() has been removed).
>
There is no longer a single collection of ActionMappings -- there is one
per application module. So you'll need to do the following to get an
ActionMapping:
ApplicationConfig appConfig = (ApplicationConfig)
request.getParameter(Action.APPLICATION_KEY);
ActionMapping mapping = (ActionMapping)
appConfig.findActionConfig("/bar");
>
> If I am to bite the bullet right now and rearchitect the
> webapp with the new struts 1.1 api, I still run into a few
> issues.
>
> What I've described above is how I thought would be the proper way
> to handle "action calling other action" in the very early days of 1.0.
> There might be a better approach now. If so, I'd appreciate if someone
> could point me in the right direction.
>
Best practice is to factor the common code out and call it from both
actions, so you don't have to do any form of "chaining" or "nesting".
> If I am to simply migrate the above code to the new 1.1 apis,
> it appears that I'd have to do the following:
>
> ActionServlet actionServlet = getServlet();
> ApplicationConfig appConfig = mapping.getApplicationConfig();
> RequestProcessor rp = actionServlet.getRequestProcessor(appConfig);
>
> It appears that "findMapping()" has been deprecated. So the code
> ActionMapping targetMapping = actionServlet.findMapping("/bar.do");
> should be replaced by
> ActionConfig targetAction = appConfig.findActionConfig()
>
You have to look up the correct ActionConfig from the ApplicationConfig,
and cast it to ActionMapping (for backwards compatibility).
> The problem though is that the execute() method of an Action expects
> an ActionMapping object... which means that I'm back to want to use the old
> 1.0 api to get an ActionMapping (or I'm once again missing something).
> How come the new execute() method of Action does not take an ActionConfig
> object as argument instead of the old ActionMapping?
>
The ActionMapping class in 1.1 is a subclass of ActionConfig, and that is
the class actually used in the configuration file parsing. So the cast
will always work.
> Finally, it would be preferable to migrate to the new RequestProcessor interface.
> However, ActionServlet.getRequestProcessor() is protected,
> preventing me from accessing it from my Action code.
> Any reason why it is not public?
Because you shouldn't be messing around with this stuff in the first place
:-).
Actually, the RequestProcessor instance that is processing the current
request can be acquired directly, from the same place that ActionServlet
gets it:
String key = Action.REQUEST_PROCESSOR_KEY + appConfig.getPrefix();
RequestProcessor processor = (RequestProcessor)
servlet.getServletContext().getAttribute(key);
The only difference is that the ActionServlet.getRequestProcessor() method
will lazilly instantiate the request processor the first time. By the
time you execute the above code in an Action, you will not have to worry
about that.
>
> Many thanks for any answer/advice...
>
> -- Pierre
>
Craig
--
To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]>
For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
