my dog learned polymorphism
The moose likes JSP and the fly likes EL implicit objects - MVC ? Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » JSP
Bookmark "EL implicit objects - MVC ?" Watch "EL implicit objects - MVC ?" New topic

EL implicit objects - MVC ?

Muni K Reddy
Ranch Hand

Joined: Aug 23, 2007
Posts: 74
Hi Guys,
The following EL implicit objects:
  • param
  • paramValues
  • cookie
  • header
  • headerValues

  • Is it a good practise to use any of the above?
    [ September 01, 2007: Message edited by: Muni K Reddy ]
    Ben Souther

    Joined: Dec 11, 2004
    Posts: 13410

    As with any tools, I would say it's got more to do with how you use them then whether or not you use them.

    Personally, I like to have all of my business logic and non-view decisions figured out before I forward to the JSP and then use JSTL and EL for help building up the markup only.

    With that line of thinking, I can't picture myself using, cookie, header or headerValues in a JSP. A case may come up but, usually, if I'm reading headers, it's because I want to branch on them and make the app behave differently according to their values or because I'm logging something like a referrer header. Neither of these things are things I would typically do in the view.

    For a small app, I might use the param object for re-populating a form that has failed validation but, in most cases, by the time validation fails, I've already used those parameters to populate a bean and it's easier (or clearer) to use the bean's properties to repopulate the form.

    Your mileage may vary.

    Java API J2EE API Servlet Spec JSP Spec How to ask a question... Simple Servlet Examples jsonf
    Muni K Reddy
    Ranch Hand

    Joined: Aug 23, 2007
    Posts: 74
    Thanks Ben!
    Chris Corbyn
    Ranch Hand

    Joined: Jan 14, 2007
    Posts: 114
    I agree with Ben in that you are probably best dealing with business logic before you get as far as the template. I'd probably consider it a bit of a code smell if you feel the need to tinker with the response headers, cookies etc in a template. I'd be taking a step back and havig a coffee to think things over at that point ;)

    The only things I deal with in the view layer are model data which I'm rendering a view for, view helpers and very occassionally an arbirtrary request parameter.

    It makes sense for EL to make them available for ad-hoc times when you may find a need for them, but I wouldn't encourage putting that sort of logic in templates much.
    I agree. Here's the link:
    subject: EL implicit objects - MVC ?
    It's not a secret anymore!