Even we had a similar problem in our application: Agree that making the ActionForm scope to be "session" may cause problems, but storing the information in request scope and copying all that information in html and then sending it back to the server again may cause extra network traffic.
We adopted following workaround for this. 1. Make most of the ActionForm scope as "session", and write a cleaning mechanism which could keep cleaning up the HTTP session on some basis. What we adopted was "as soon as the user shall operate on the top drop down menu of the application, it shall remove any ActionForms more than last 5.(This "5" was configurable). This keeps the HTTP session lighter. 2. For the screens that have ActionForm scope defined as "request", some information was stored in HTML hidden variables but there was special mechanism for collection objects. For every such screen one object was stored in HTTP session and this object stored all collection objects. Hope you too find this solution good for your application. Regards Puneet ----- Original Message ----- From: "Phase Web and Multimedia" <[EMAIL PROTECTED]> To: "Struts User List" <[EMAIL PROTECTED]> Sent: Tuesday, January 14, 2003 12:31 AM Subject: Collection Population Post-Validation Best Practice > In the past I have not done any validation in my ActionForm so I have never > ran across this problem. I read a post from a while back regarding this but > the feedback was fairly obscure. I also read in "Struts In Action" regarding > this problem. But, the solutions were a little vague. So, I am looking for > some creative specificity. > > Problem: > > I prepopulate some collections in an ActionForm through an Action class > before I display the jsp form. I use the collections that I populate in the > form to create the drop down (<html:options collection="foo">). Upon > submittal of the jsp form and a failed validate in my ActionForm i return > back to the jsp page and my collections are not available/null (of course) > because my form is set in request scope. Following are a few possible > solutions ,that came to mind, for re-populating my collections prior to > being sent back to ActionMapping's input. I am just wondering which is the > best or if there are some better solutions. > > 1) Specify the form as a session scope - I don't really want to do this > because I am concerned that as the usage volume goes up I am potenially > going to be passing around large complex objects in the session. I prefer to > keep it in the request. > > 2) Call my logic classes that populate the collections set the values > (setXXX(), getXXX())from within the validate method prior to returning the > ActionErrors. - I am not sure how this would work using Validator. Can I > override validate when extending ValidatorActionForm and call super() to > make sure that the Validator validation is called and then run my logic > classes to repopulate the form? > > 3) Set my ActionMapping's input to go to the Action url rather than the jsp > (This was a suggestion in "Struts In Action") - I tried this but I get some > looping and ultimately a StackOverflowError. See Following: > > java.lang.StackOverflowError > at java.util.HashMap.hash(HashMap.java:257) > at java.util.HashMap.removeEntryForKey(HashMap.java:518) > at java.util.HashMap.remove(HashMap.java:507) > at > org.apache.catalina.core.ApplicationHttpRequest.removeAttribute(ApplicationH > ttpRequest.java:231) > ... > at > javax.servlet.ServletRequestWrapper.removeAttribute(ServletRequestWrapper.ja > va:340) > at > org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher. > java:676) > at > org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatch > er.java:431) > at > org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher > .java:355) > at > org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:10 > 33) > at > org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcesso > r.java:269) > at > org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(Requ > estProcessor.java:980) > at > org.apache.struts.tiles.TilesRequestProcessor.internalModuleRelativeForward( > TilesRequestProcessor.java:336) > at > org.apache.struts.action.RequestProcessor.processValidate(RequestProcessor.j > ava:950) > at > org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:255) > at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1422) > at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:523) > at javax.servlet.http.HttpServlet.service(HttpServlet.java:760) > at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) > ... > at > org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher. > java:683) > at > org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatch > er.java:431) > at > org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher > .java:355) > at > org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:10 > 33) > at > org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcesso > r.java:269) > at > org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(Requ > estProcessor.java:980) > at > org.apache.struts.tiles.TilesRequestProcessor.internalModuleRelativeForward( > TilesRequestProcessor.java:336) > > 4) Make sure I have an html representation of the collection in a form - > This idea just seems preposterous. > > Thanks ahead of time for the info. > > Brandon Goodin > Phase Web and Multimedia > P (406) 862-2245 > F (406) 862-0354 > [EMAIL PROTECTED] > http://www.phase.ws > > > > -- > To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> > For additional commands, e-mail: <mailto:[EMAIL PROTECTED]> > > -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
