code: protected ModelForm getModelForm(ModelHandler modelHandler, ActionForm actionForm, HttpServletRequest request) throws Exception {
  
  		if (actionForm == null) {
  			throw new Exception(" must define form-bean as 'action' name in struts-config.xml ");
  		}
  		ModelForm strutsForm = (ModelForm) actionForm;
  		String action = strutsForm.getAction();
  		if ((action == null) || (action.length() == 0))
  			throw new Exception(" Need a field : <html:hidden property=action /> in jsp's form! ");
  
  		return strutsForm;
  
  	}
docs: get a ModelForm or create it.