params in jsp:setProperty in .tag file won't accept el

I know the tag is actually loading because it's printing out the Test, the Hi and correctly filling in whatever I put into the prefix attribute.

However, it's not setting the attributes in the bean.

What in the sam hill? Why won't this work?

Is the property mutator being called? If so, what value is being passed to it?

The mutator is not being set.
I did some experiments. I can:

a. Set a jsp:setProperty directly in the jsp at the place where I previously used the tag (right after the jsp:useBean)

b. Set the jsp:setProperty directly in the tag (ie, not using el in the param, just setting the param directly)

c. Inside the .tag file, I can output the value that I pass into the prefix attribute

However, when I try to set information in the jsp:setProperty's param attribute in the .tag file, and that information I want to set comes from the .tag file's attribute, it doesn't work.
Does this mean you can't set the attributes of markup inside tags using expression language?

[ September 21, 2006: Message edited by: Jacob Fenwick ]
[ September 21, 2006: Message edited by: Jacob Fenwick ]

Where is mybean set up?

I'm instantiating mybean using a jsp:useBean in the jsp that calls this tag. I know that I can access both from the parent jsp page and from within the .tag file from experiments a and b.

Here is a more concise example of the problem with all the code:

TestBean.java

test.tag

tagtest.jsp

The html output I get when I call tagtest.jsp?footable=test is:

And the Tomcat output is:

If anyone has any insight into this let me know. Maybe .tag files can't access the bean somehow?

Is the "Setting table" diagnostic being emitted?
[ September 25, 2006: Message edited by: Bear Bibeault ]

No it's not, so somehow the reflection is failing when the jsp:setProperty is called in test.tag.
[ September 25, 2006: Message edited by: Jacob Fenwick ]

Then the problem is clearly not in the EL but in the setProperty.

That's where you'll need to dig.

By the way, why are you using setProperty rather than <c:set>? I haven't used setProperty in years.

I realized that the jsp:setProperty is being called first, then the EL is being evaluated. I confirmed this by calling tagtest.jsp this way:

This produced the correct html output.

I'm trying to rewrite the jsp:setProperty to use a c:set but I'm a little stuck. This is what I have:

I need to find a way to concatenate the prefix attribute and some string together, and append that to the param. . I don't think there's a way to do that, so I'll probably have to abandon doing this in a .tag file.

I see this as a weakness of c:set. If I had stuck to scriptlets and jsp:setProperty I would have had more control (or maybe not, maybe the jsp:setProperty is called even before the scriptlets).

I need to find a way to concatenate the prefix attribute and some string together,

${prefix}someString

That won't work. What I'm trying to do is something like this:

I know that won't work but that's approximately what I want to do.
I want to fill the value of the c:set with the request parameter called prefix+table. So if I pass foo into the prefix attribute of that .tag file then the request parameter will be footable.

I don't think this will actually be possible.

Of course it is possible.

The jsp:setProperty tag wouldn't work, because the "param" attribute will not accept runtime expressions. I'm pretty sure it would just pass the value through as a string without evaluating it.

For the JSTL, I think you will have to do it in two steps
1 - generate the parameter name
2 - set the value

Hooray!
Thanks Bear, Stefan.