Redisplay info when a user goes back to previous page

[darren schild]

I am having trouble redisplaying the information the user entered on a previous screen.
I have a "prev" and "next" bottom.
If the user wants to correct some information on the "prev" screen. Upon their return, the information is gone and they have to re-enter the information?!?
If I do a <jsp:getProperty> I get an null object exception.
Any help/suggestions/sample code?
Thanks much!

[Rene Larsen]

You have to save the request from the current page in e.g. a HashMap in e.g. Session. Then run the Map through when you 'reenter' the page and parse the values to the fields.
/Rene

[darren schild]

Thanks for the reply, I'm a newbie so that is part of the problem.
I am using a session, whether I'm setting it up right is another question.
The exception comes on the first time thru when I make a call to the Bean and I get the exception:
org.apache.jasper.JasperException: Attempted a bean operation on a null object.
On the call to:
<jsp:getProperty name="customer" property="firstName" />
This probably isn't enough information but any ideas???

[Rene Larsen]

Just a question - do you only use JSP or are you in for Servlet as well?
/Rene

[Rene Larsen]

I've made a sample:
first.jsp

<jsp:useBean id="UserInfo" scope="session" class="dk.rlarsen.slots.logon.Userinfo"/>
<%@ page import="java.util.*" %>
<%!
   Map reqMap;
<%
<%
   if (UserInfo == null) {
      UserInfo = new dk.rlarsen.slots.logon.Userinfo();
   }
   reqMap = (HashMap) UserInfo.getFirstRequestMap();
%>
<table border="0" cellspacing="0" cellpadding="0">
   <form method="post" name="FirstForm" action="second.jsp">
      <tr>
         <td width="100">Brugernavn:</td>
         <td align="right" width="200">
           <input type="text" name="userid" size="25" maxlength="32" value="<%= (reqMap == null || reqMap.get("userid").equals("")) ? "" : (String) reqMap.get("userid") %>">
         </td>
      </tr>
   </form>
</table>

second.jsp, next.jsp....

<jsp:useBean id="UserInfo" scope="session" class="dk.rlarsen.slots.logon.Userinfo"/>
<%@ page import="java.util.*, dk.rlarsen.slots.bean.*" %>
<%!
   Map reqMap;
<%
<%
   if (UserInfo == null) {
      UserInfo = new dk.rlarsen.slots.logon.Userinfo();
   }
   try {
      reqMap = HelperBean.httpToHash(request);
   }
   catch (Throwable t) {
      /* some action */
   }
   UserInfo.setFirstRequestMap(reqMap);
   session.setAttribute("UserInfo", UserInfo);
   reqMap = (HashMap) UserInfo.getNextRequestMap();
%>
<table border="0" cellspacing="0" cellpadding="0">
   <form method="post" name="SecondForm" action="next.jsp">
      <tr>
         <td width="100">Brugernavn:</td>
         <td align="right" width="200">
           <input type="text" name="userid" size="25" maxlength="32" value="<%= (reqMap == null || reqMap.get("userid").equals("")) ? "" : (String) reqMap.get("userid") %>">
         </td>
      </tr>
   </form>
</table>

HelperBean.java

import java.util.*;
import javax.servlet.http.*;
public class HelperBean {
   public static Map httpToHash(HttpServletRequest aHttpRequest) throws Throwable {
      Map map = new HashMap();
      for (Enumeration e = aHttpRequest.getAttributeNames(); e.hasMoreElements();)  {
         String name = (String) e.nextElement();
         Object o = aHttpRequest.getAttribute(name);
         if (o instanceof String) {
            map.put(name, o);
         }
      }
      for (Enumeration e = aHttpRequest.getParameterNames(); e.hasMoreElements();)  {
         String name = (String) e.nextElement();
         String sValue = aHttpRequest.getParameter(name);
         map.put(name, sValue);
      }
      for (Enumeration e = aHttpRequest.getSession().getAttributeNames(); e.hasMoreElements();)  {
         String name = (String) e.nextElement();
         Object oValue = aHttpRequest.getSession().getAttribute(name);
         if (oValue instanceof String) {
            map.put(name, oValue);
         }
      }
      return map;
   }
}

Just to give you an idea.
/Rene
[ July 17, 2002: Message edited by: Rene Larsen ]

[darren schild]

Thanks for the help!
I am using a servlet, JSPs & a bean.... Haven't worked, much, with hashmaps but i'm getting there.....
So, I have 3 JSPs a contact.jsp, a contactInfo.jsp and a contactDisplay.jsp, along with the Contact(servlet) and ContactCustomer(bean). When I fill out the contact page the request is then forwarded to the contactInfo.jsp when I hit "prev" to go back and edit, everything is gone.
It's gotta be something simple but.........

[Rene Larsen]

Well, as I can read from your post, the sample I just gave you will fulfil what you need
/Rene