Dynamic variable name in JSTL

[Mal Charlton]

Hi

Does anyone know how i can get a value (with a dynamic name, evaluated at runtime) off the request?

Here's an example...

In a Struts action, I add 2 attributes to the request:

Employee empObj = new Employee();
empObj.setManagerId(1);
request.setAttribute("employee", empObj);
request.setAttribute("1", "MrManager"); // name which relates to that managerId.

Then in my JSP, i want to get the manager name as follows:

<c:set var="employee" value="${employee}" scope="request"/>
<c:set var="managerName" value="${<c :o ut value='${employee.managerId}'/>}" scope="request"/>
<c :o ut value='${managerName}'/>

I'd like the final <c ut> to return "MrManager".

Is this possible with JSTL 1.0.4? If anyone knows, i'd really appreciate some help. This is bugging me out

Thanks.

Malcolm
[ May 09, 2005: Message edited by: Mal Charlton ]

[Bear Bibeault]

"Mal J C",

We're pleased to have you here with us on the Ranch, but there are a few rules that need to be followed, and one is that proper names are required. Please take a look at the JavaRanch Naming Policy and adjust your display name to match it.

In particular, your display name must be a first and a last name separated by a space character, and must not be obviously fictitious.

Thanks!
bear
Forum Bartender

P.S. When posting code, checking the 'disable smilies' box will keep your <c:out> tags from looking so surprised.

[Bear Bibeault]

Firstly,

request.setAttribute("employee", empObj);
request.setAttribute("1", "MrManager");

you imply a relationship here but I see none. What is the significance of the hard-coded "1"? Is it the employee ID? There's no way of knowing.

Next,

 <c:set var="employee" value="${employee}" scope="request"/> 

performs no operation. "employee" is already on the request, why replace it with itself?

And,

 <c:set var="managerName" value="${<c:out value='${employee.managerId}'/>}" scope="request"/> 

you cannot nest actions (tags) within other tags like this.

If what you are trying to do is what I suspect you are trying to do: that is, use the property of a scoped variable as a way to look up another scoped variable, try something along the lines of:

<c:out value="${requestScope[employee.managerId]}"/>

[Mal Charlton]

Thanks for the quick reply, Bear

I'll address your points in order:

1. I've corrected my display name.
2. "1" was the manager ID in the example

Employee empObj = new Employee();
empObj.setManagerId(1);
request.setAttribute("employee", empObj);
request.setAttribute("1", "MrManager"); // name which relates to that managerId.

3.

 <c:set var="employee" value="${employee}" scope="request"/> 

I thought i had to explicitly declare the variable to be able to use it on the JSP, but now i know better. Thanks for the tip!


4.

 <c :o ut value="${requestScope[employee.managerId]}"/> 

This is probably what i'm looking for. However, my real problem is a bit more complicated...

Suppose i have this situation:

Employee e = new Employee();
e.setManagerId("100")
e.setDepartmnt("Sales");
request.addAttribute("employee", e);
// now use these 2 attributes to form a key, to add something else to the request
String key = e.getManagerId()+"|"+e.getDepartmnt()+"|Name"; // "100|Sales|Name"
request.addAttribute(key, "Bob");

Now, on the JSP, how would i get "Bob" off the request using the Employee object? I'm not sure on the syntax. Would it be something like...

<c :o ut value="${requestScope[employee.managerId+'|'+employee.department+'|Name']}"/>

?
[ May 09, 2005: Message edited by: Mal Charlton ]