Question

Currently I’m getting data in jsp using scriptlet but now want to use JSTL so I’m trying to convert my scriptlet code to JSTL. But for following scenario I don’t know how to get data in jstl.

Let me explain by example:

There are 3 objects

1. User (user_id, username, password)
2. Box (box_id, box_name,list_of_boxCat)
3. BoxCat (box_cat_id,box_id,user_id,cat_name)

Now I need to display list of boxes a user own. So i have created a list of Box objects by firing query in servlet and pass that list in jsp in request attribute then access it in jsp. Until this everything goes fine. But now I have to access BoxCat object which do not have any reference from Box object directly. To get BoxCat object I have to combine Userid and Box id and then I can get BoxCat id. So in scriptlet I call my DAO and get list by running query. But I don’t know how to do this JSTL. Anyone please help me on how to do this?

Answer 1

You should redesign or map your model so that it suits whatever your view needs. Does the view need a List<BoxCat> as a property of User or maybe BoxCat as a property of Box? If so, then make that so and change your controller and DAO to fill that beforehand.

Otherwise you will end up in clumsy and potentially memory-inefficient workarounds using a mapping of the entities by their ID such as Map<Long, Entity>.