Question

So according to my JSP reference book, as well as every other reference I can find on the web, I’m supposed to be able to do something like:

<%@ tag dynamic-attributes='dynamicAttributesVar' %> 

and then when someone uses an attribute that I didn’t define in an attribute directive, I should be able to access that attribute from the ‘dynamicAttributesVar’ map:

<%= dynamicAttributesVar.get('someUnexpectedAttribute') %> 

However, that doesn’t work, at all; I just get a ‘dynamicAttributesVar cannot be resolved’ error when I try.

Now, I did discover (by looking at the generated Java class for the tag) that I can ‘hack’ a working dynamic attributes variable by doing:

<% Map dynamicAttributesVar = _jspx_dynamic_attrs; %> 

Now, that hack doesn’t work unless I also use the dynamic-attributes parameter on my tag directive, so it seems that the parameter is doing something.

But what I want to know is, how can I make it do what it does for every other JSP user out there?

Answer 1

Isn’t ‘dynamicAttributesVar’ the name of the key in the page context that the dynamic attributes are put into? So you could do

<c:out value='${dynamicAttributesVar.someUnexpectedAttributes}'/> 

or if you must use scriptlets:

Map dynamicAttributes = (Map) pageContext.getAttribute('dynamicAttributesVar') 

(Disclaimer: I haven’t tried it, I’ve just used dynamic attributes in tags with direct Java implementations… but it seems reasonable)