ViewObject is null ?

Question

I’m developing a jsp application with bc4j using jdev 10g. I have a problem with viewobjects in the application module suddenly becoming null. It doesn't happen every time and it seems to depend on the computer environment as well. It works fine in the development environment, but when I transfer the application to my clients environment I am getting the error. The error happens in dataAction class. I have tried to place the code in findForward method and prepareModel method but the result is the same. Debugging the application I found that mViewObjects and mViewLinks in the application module become null at some point. The action gets executed a couple times and it works fine and then it breaks down.
I can't see what is causing the problem. Below is the code of the dataAction. 'bindContainer' and 'module' in the prepareModel method are not null, but 'view' becomes null. It is also interesting that the data on the page (from the same view) is displayed correctly.
public class FindSredstvaViewPageAction extends DataAction
String page;
protected void findForward(DataActionContext actionContext) throws Exception
//Postavi page attribute tako da se otvori stranica na kojoj je current row, SredstvaView
actionContext.getHttpServletRequest().setAttribute(MyGlobals.PAGE, page);
// TODO: Override this oracle.adf.controller.struts.actions.DataAction method
super.findForward(actionContext);
private String getPage(int index)
int rows_per_page = MyGlobals.ROWS_PER_PAGE;
int page = 0;
while(true)
if(index < 0) break;
if(index == 0) // prvi red na strani
page ++;
break;
index = index - rows_per_page;
page ++;
return String.valueOf(page);
protected void prepareModel(DataActionContext actionContext) throws Exception
DCBindingContainer bindContainer = actionContext.getBindingContainer();
StalnaSredstvaModuleImpl module = ((StalnaSredstvaModuleImpl)actionContext.getBindingContainer().getApplicationModule());
SredstvaViewImpl view = module.getSredstvaView();
page = getPage(view.getCurrentRowIndex());
// TODO: Override this oracle.adf.controller.struts.actions.DataAction method
super.prepareModel(actionContext);

Answer 1

Hi,
Please use DCDataControl.getDataProvider() to acquire an AM reference. Because your logic is implemented before prepareModel DCBindingContainer may reference an uninitialized AM reference from a previous request (I filed bug 3829746 to resolve this issue).
Also, it is not recommended that you downcast to an AM "Impl" class in client side code. This will prevent your code from being redeployed in different configurations (immediate vs. batch). Instead of downcasting to the "Impl" class you may export the VO getter to a remote AM interface using the AM wizard and then downcast to the AM interface or use findViewObject(String) on the base ApplicationModule interface.
Hope this helps,
JR