Re: Two ActionForms colliding on property name
Yet another reason to not use Action chaining. Maybe you could rethink why you're chaining the actions. David From: Derek Richardson [EMAIL PROTECTED] Reply-To: Struts Users Mailing List [EMAIL PROTECTED] To: Struts Users Mailing List [EMAIL PROTECTED] Subject: Two ActionForms colliding on property name Date: Mon, 27 Jan 2003 15:43:05 -0500 I have one action forwarding to another action. The first action and the second action both have form-beans specified using the name attribute and these form beans are different. Unfortunately, these two ActionForms each have an attribute named value, but in ActionForm one it is a String, while, in ActionForm two, it is a List. You probably already see the problem. Here is what I think it is. When a JSP submits to the first action, there is a request parameter called value which is a String. When the first action forwards to the second, ActionForm two is populated from the request, the string is found in place of the list, and I get BeanUtil.populate() errors. Any suggestions (other than changing the attribute names, which is a possibility, but not my preference)? Thanks, Derek Richardson Here's the error, if you're interested: type Exception report message Internal Server Error description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request. exception javax.servlet.ServletException: BeanUtils.populate at org.apache.struts.util.RequestUtils.populate(RequestUtils.java:980) at org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:779) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:246) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1292) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510) 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(ApplicationDispatcher.java:431) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:355) at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1014) at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:417) at org.apache.struts.action.RequestProcessor.processActionForward(RequestProcessor.java:390) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:271) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1292) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510) at javax.servlet.http.HttpServlet.service(HttpServlet.java:760) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012) at
RE: Two ActionForms colliding on property name
I have gone back and read the posts on action chaining to October 21 2002. If I need to go back further, let me know. I have rethought why I am chaining the actions and this is what I have come up with. As I understand it, this is the popular and well-liked Struts convention: Action1 - JSP1 - Action2 - JSP2 - Action3 - JSP3 - ... - ActionN - JSPn This seems somewhat messy to me because a single Action has to handle both post-processing the last JSP and pre-processing the next JSP. For instance, Action2 has to both do whatever it has been asked to do by JSP1 and also prepare for the display of JSP2. So, (1) Action2 will first take some input from JSP1 and save it to the model and then (2) read some other data from the model and package it up for JSP2 to consume. This strikes me as two logically separate concerns being coupled together in a single non-cohesive action. The model that is more intuitive to me is: PreAction1 - JSP1 - PostAction1 - PreAction2 - JSP2 - PostAction2 - ... - PreActionN - JSPn Of course, in some cases the post-processing of the last request *is* closely linked to the preprocessing of the next response. In this situation, the current convention works well. However, imagine the case of coming out of the last JSP in an Add Foo wizard. You want to (1) save the new Foo and (2) redisplay the list of all Foos so the user can decide what to do next. These two activities are not closely linked. Additionally, consider that you also can come out of a Delete Foo page where you want to (1) delete the outdated Foo and (2) redisplay the list of all Foos so the user can decide what to do next. Not only are the activities not closely linked, but it sure would be nice to have an Action that encapsulates the common activity #2 so that code doesn't have to be duplicated. Notice, in this case, there is no pollution of the Action by business logic: all the action does is call a method on the business logic facade to get a Collection of Foos and then put it in the request scope. I don't see any non-cumbersome way of eliminating this duplication without action chaining of the restricted type I am talking about. In short, some of my Actions prepare data for a JSP to display. I can't forward to the JSP without preparing the data first. I may want to forward to the same JSP from several different places in my workflow. I don't want to duplicate the data preparation code in several different places in my workflow. Is there a solution for me other than action chaining? FYI, I am halfway through the Cavaness book and don't remember seeing action chaining discussed. I have not read any other of the Struts books. If what I am asking is covered in depth somewhere else, a short summary and a clear citation that will let me find the resource is appreciated. Thanks, Derek Richardson -Original Message- From: David Graham [mailto:[EMAIL PROTECTED]] Sent: Monday, January 27, 2003 3:51 PM To: [EMAIL PROTECTED] Subject: Re: Two ActionForms colliding on property name Yet another reason to not use Action chaining. Maybe you could rethink why you're chaining the actions. David From: Derek Richardson [EMAIL PROTECTED] Reply-To: Struts Users Mailing List [EMAIL PROTECTED] To: Struts Users Mailing List [EMAIL PROTECTED] Subject: Two ActionForms colliding on property name Date: Mon, 27 Jan 2003 15:43:05 -0500 I have one action forwarding to another action. The first action and the second action both have form-beans specified using the name attribute and these form beans are different. Unfortunately, these two ActionForms each have an attribute named value, but in ActionForm one it is a String, while, in ActionForm two, it is a List. You probably already see the problem. Here is what I think it is. When a JSP submits to the first action, there is a request parameter called value which is a String. When the first action forwards to the second, ActionForm two is populated from the request, the string is found in place of the list, and I get BeanUtil.populate() errors. Any suggestions (other than changing the attribute names, which is a possibility, but not my preference)? Thanks, Derek Richardson Here's the error, if you're interested: type Exception report message Internal Server Error description The server encountered an internal error (Internal Server Error) that prevented it from fulfilling this request. exception javax.servlet.ServletException: BeanUtils.populate at org.apache.struts.util.RequestUtils.populate(RequestUtils.java:980) at org.apache.struts.action.RequestProcessor.processPopulate(Req uestProcessor.java:779) at org.apache.struts.action.RequestProcessor.process(RequestProc essor.java:246) at org.apache.struts.action.ActionServlet.process(ActionServlet.j ava:1292
