Hello all
Has anybody successfully used Stuts tags and Custom tags together?
For example:
Consider a custom tag with the following code:
out.println("<html:link action=\"Update.do\">" + entry[ix] + "</html:link>");
The custom tag appears to write the output directly to the socket without further Struts
tag evaluation, consequently the HTML source on the browser includes "html:link" which
it doesn't understand.
1. How about writing the link using <a href=/WEB-INF/pages/update.jsp></a>
When I do this I lose the connection to my current session. Not a solution.
2. Try return true in the "theBodyShouldBeEvaluatedAgain" method.
I tried this and the code got into a loop (I believe this simply recurses back through my
code). If I am supposed to use this somebody will need to tell me a simple way of
stopping the recursion.
3. The only other alternative I have is to look into the Struts source code and try and
find some internal method to call to evaluate the generated code before I print it to the
socket.
Hope somebody has tried to do this before
Kind regards
mc
FCUS Computing
Mob: 0415 24 26 24
murray (AT) focus-computing (DOT) com
http://www.focus-computing.com

From: "Murray Collingwood" <murray (AT) focus-computing (DOT) com>

Has anybody successfully used Stuts tags and Custom tags together?

For example:
Consider a custom tag with the following code:
out.println("<html:link action=\"Update.do\">" + entry[ix] +
"</html:link>");

I haven't done anything with custom tags in a while, but isn't this the same
as writing (in a JSP):
<my:tag attr="<other:tag action="abc"/>"/>
? Which, as you've noted, won't work.

What does your custom tag do? The 'entry[ix]' looks like it might be
iterating. If so can you do it with <c:forEachand <html:linkalone?
Alternately, do you really need the <html:linkor can you just write an <a
href=""directly?

Murray Collingwood wrote:
Hello all

Has anybody successfully used Stuts tags and Custom tags together?

For example:
Consider a custom tag with the following code:
out.println("<html:link action=\"Update.do\">" + entry[ix] + "</html:link>");
>
The custom tag appears to write the output directly to the socket without further Struts
tag evaluation, consequently the HTML source on the browser includes "html:link" which
it doesn't understand.

This says 'write the text "<html:link " to the HTTP response', as you
say. It seems that what you are trying to do is create a custom tag which
outputs JSP source, which you then want processed as if it had appeared
literally in the JSP page. In other words, you want to write '<x:mytag/>'
in the JSP and have the rendered result be as if you'd actually written
'<html:link '. Is that right?

1. How about writing the link using <a href=/WEB-INF/pages/update.jsp></a>
When I do this I lose the connection to my current session. Not a solution.

What do you mean by 'loose the connection to my current session?' Do you
mean that when the link is clicked the resulting request isn't associated
with the session? If cookies are enabled it should be, but if cookies are
turned off you need to include the session ID in the URL the same as Struts
and JSTL tags do.

2. Try return true in the "theBodyShouldBeEvaluatedAgain" method.
I tried this and the code got into a loop (I believe this simply recurses back through my
code). If I am supposed to use this somebody will need to tell me a simple way of
stopping the recursion.

Evaluate Body is used when you want the body of the tag to be evaluated,
not when you want the /output/ of the tag to be evaluated. Think, for
example, of forEach and the like.

3. The only other alternative I have is to look into the Struts source code and try and
find some internal method to call to evaluate the generated code before I print it to the
socket.

I think it would help to take a step back and describe the overall problem
you're trying to solve. If I understand you correctly, you're trying to
write a custom tag that generates JSP source code and have that generated
JSP code evaluated inline as part of the same processing cycle that calls
your custom tag. I suspect there are easier ways to do what you need

If all you want to do is include a link in the HTML (not JSP) markup
generated by your tag and ensure that link includes JSESSINID when needed,
try looking at the code for the <html:link/tag to see how the session ID
and URL rewriting is handled.

HTH,

L.

Thanks for the responses to my question.

I agree totally with what you are saying, to try generating Struts tags from a Custom tag
is completely the wrong approach - I can see that now (you know, "I see the light" :-)

Let me explain what I am trying to do, maybe somebody can point me in the right
direction.

My website provides a login capability and each user has a security setting, this is just a
number (security isn't too complicated). Number 0 can simply browse around and make
comments etc. Security number 5 is allowed to manage the content, add and update
database records that contain data that appear on the site. Number 3 is allowed similar
content management access but only on certain records.

When I display a page that contains some database records I then want to display
"Update" and "Delete" links next to the appropriate data.

I could use a <logic:greaterThantag to test the value of the security number and
then display the link if appropriate. This gets more complicated when the security
number 3 is used, as then I have to test values on the record as well, suddenly I have
nested <logic:tags and the page is starting to look a lot more complicated than it
should. The other problem with this approach is: "whether a user can update a record
or not" is a business logic decision and shouldn't be in the interface.

Now, to complicate it even further, security number 2 is allowed to update records but
uses a different form, in other words, they are only allowed to update certain values on
the record. Hence I have to vary the link generated in some instances.

I hope you are getting the picture. This is why I was trying to use a custom tag that
could still interact with my model, call business methods to make security decisions and
vary the generated link accordingly.

And finally the question: How should I go about writing the "Update" link now that we all
understand the problem?

Thanks in advance.

Kind regards
mc

19 Aug 2005 at 15:30, Craig McClanahan wrote:

8/18/05, Murray Collingwood <murray (AT) focus-computing (DOT) comwrote:
Hello all

Has anybody successfully used Stuts tags and Custom tags together?

For example:
Consider a custom tag with the following code:
out.println("<html:link action=\"Update.do\">" + entry[ix] + "</html:link>");

Your question doesn't really describe what you are illustrating
which appears to be that you want to dynamically create a *JSP* page,
then have the page compiled and executed, on every request. You're
going to find that this solution is not practical, and that you should
take another approach.

When you first start a webapp, you notice the slight delay when you
access a JSP page the first time, so that it gets compiled? Even if
you jumped through all the technical hoops to output a JSP file and
get it compiled (technically feasible), you're going to be imposing
that kind of overhead on *every* request, instead of just the first
request for that page. Even if everything else in your app was
instantaneous, the response time of your app would be awful.

A far better approach for the particular case you are using here is to
use either an expression or some subordinate tag to calculate the
dynamic part of your output. Assume for a moment that your Struts
action puts the "entry" array into request scope. Now you can do
something like:

<html:link action="Update.do">
<c:out value="${entry[3]}"/>
</html:link>

course, the reason you probably want to do this in the first place
is that you want to create a bunch of links so put the same sort
of structure inside a looping tag (renaming the request scope
attribute containing your array to be "entries" to be more readable):

<c:forEach var="entry" items="entries">
<html:link action="Update.do">
<c:out value="$entry"/>
</html:link>
</c:forEach>

The <c:forEachtag exposes the current element in the array as a page
scope attribute named by the "var" attribute, and you can therefore
reference the current element directly inside the loop.

Craig

To unsubscribe, e-mail: user-unsubscribe (AT) struts (DOT) apache.org
For additional commands, e-mail: user-help (AT) struts (DOT) apache.org

I hope you are getting the picture. This is why I was trying to use a
custom tag that could still interact with my model, call business methods
to make security
decisions and vary the generated link accordingly.

And finally the question: How should I go about writing the "Update" link
now that we all understand the problem?

You could put all that logic somewhere else, perhaps in a bean with an
'isUpdateAllowed' method:
<c:if test="${security.updateAllowed}<html:link </c:if>

Since you're already okay with a custom tag, what about extending the Struts
link tag to do what you need?

I also wonder if you really need <html:linkfor this-- you're already
hard-coding the action name. If there's nothing dynamic about the link
other than that 'entry[ix]' part, then can you just write out the <a
href=""from your custom tag?

I've had success with request.isUserInRole-- *without* getting into custom
Realms and CMA-- just add a Filter, wrap the request and override
'isUserInRole'. It sounds like you have some "levels" that could be roles.
(I'm not clear on the runtime checking of fields you mentioned, but you
should have access to the request and session from isUserInRole.) Struts
has <logic:present role=""(and there's probably a JSTL equivalent).