Scriptlet - can't change bean instance reference?

Question

I am having trouble assigning a reference of a bean to an entirely new object.
What I am trying to do here is replace my cartDetailBean with a de-serialized version from the database.
I have written a utility class called BlobTool which returns an Object. In this case, I expect the Object to be of type CartBean.
<jsp:useBean id="cartDetailBean" class="com.abctech.myapp.CartBean" scope="page"/>
<jsp:useBean id="blobBean" class="com.abctech.myapp.util.BlobTool" scope="page"/>
<%
//Use a temporary cartBean in the scope of the request to inspect it's contents.
cartDetailBean = (com.abctech.myapp.CartBean)
          blobBean.getBlobFromTable("orders",
"serialized_order",
"orderid",
request.getParameter("orderid").toString());                                             
%>After this I try to access the cartDetailBean in JSTL and I get empty values, for example:
<c:out value="${cartDetailBean.customerID}"/>Has none of the values of the CartBean returned by blobBean.getBlobFromTable(...).
How can I put a bean into scope such that I can access it conveniently with JSTL tags?

Answer 1

Well you put java code where it is supposed to be. In a servlet or a java bean.
You put that java code in a servlet, set the request attribute(s) and then forward to the jsp to display the result.
Only one of those parameters to the method is dynamic.
You could write a helper class so that JSTL could access that better.
something like
public class CartHelper{
  String orderId;
  public String getOrderId(){ return orderId; }
  public void setOrderId(String orderId){this.orderId = orderId;}
  public CartBean getCart(){
    BlobTool blobBean = new BlobTool();
    CartBean cartDetailBean = (CartBean)
          blobBean.getBlobFromTable("orders",
"serialized_order",
"orderid", orderId);
    return cartDetailBean;
}and then in JSP:
  <jsp:useBean id="helper" class="com.abctech.myapp.CartHelper"/>
  <c:set target="helper" property="orderId" value="${param.orderid}"/>
  <c:set var="cartDetailBean" value="${helper.cart}"/>
This approach
- removes scriptlet code from your JSP
- removes the details of blob access, and which tables to access from the jsp
- lets you use JSTL in a semi-neat way
Cheers,
evnafets