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Converting request parameters to JSP tag-file attributes

Madhumitha Subramanian
Greenhorn

Joined: Nov 09, 2009
Posts: 7
I have a JSP that invokes a tag-file with some attributes as defined in the tag-file. I want to convert the request parameters that I receive for this JSP as attributes to the tag-file dynamically. For eg., If my JSP file is sample.jsp and it's contents are :

And I receive attr1,attr2 as request parameters in my JSP - say /sample.jsp?attr1=value1&attr2=value2..., How do I pass on the same as attributes to the tag-file?
I tried using JSTL tags in the JSP to generate run-time attributes like below, but no luck!

When I try the above code, I get

   "Expression language not allowed in a template text body."

I've declared the tag's body-content as "scriptless" with dynamic-attributes enabled. As rtexprvalue of a JSP attribute defaults to true, I don't understand why this exception occurs. Any help would be greatly appreciated!
Sudhakar Sharma
Ranch Hand

Joined: Apr 04, 2009
Posts: 71

are you passing parameter to that jsp? try <jsp:param> tag, I am also confussed in your question talking about parameter or attribute.
Frits Walraven
Creator of Enthuware JWS+ V6
Bartender

Joined: Apr 07, 2010
Posts: 1715
    
  25

Hi Madhumitha,

"Expression language not allowed in a template text body."

With the <jsp:attribute> you are defining attributes for the enclosing <c:forEach> tag, and if you do that you have to define a <jsp:body> (because the body of <c:forEach> is not defined as empty)...

I guess you want to add the parameter names and parameter values as attribute names and attribute values to the <tag:showTag>, don't you? Can you show us your tld entry or tag-file and your showTag implementation?

Have you thought of this construction?


Regards,
Frits
Madhumitha Subramanian
Greenhorn

Joined: Nov 09, 2009
Posts: 7
Hi Sudhakar and Fritz,

  Thanks for the replies.

@Sudhakar
When I try the jsp:param, I get

  "The jsp:param action must not be used outside the jsp:include, jsp:forward, or jsp:params elements"

Quite expected, as I want them to be passed on as attributes to the showTag tag and not as parameters.

@Fritz

With the <jsp:attribute> you are defining attributes for the enclosing <c:forEach> tag, and if you do that you have to define a <jsp:body> (because the body of <c:forEach> is not defined as empty)


  Alrite, this din't strike me before. So what I want to achieve looks quite impossible now Anyways, I want to add parameter name as attribute name and the parameter's value as attribute's value to the tag-file.

So when I make a request like /sample.jsp?attr1=value1&attr2=value2&...

I want to convert this to : <tag:showTag attr1=value1 attr2=value2/> in the JSP file

And my showTag.tag file is something like this :



  Trust I was clear. Any possible solution to this?
Frits Walraven
Creator of Enthuware JWS+ V6
Bartender

Joined: Apr 07, 2010
Posts: 1715
    
  25

Any possible solution to this?

Well I am still not sure what you are trying to do with this <tag:showTag>. What should the jsp do with the parameter names and parameter values? If you would have posted your implementation I could have suggested a solution. It seems you didn't like the one I posted earlier?

What about this one (making use of dynamic attributes in a tag-file)
The JSP-file:


and the tag-file

with a url of:

having a result of:

name attr2
value b
name attr1
value a

Regards,
Frits
 
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