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Tag getParent() for tag files?

 
Gili Tzabari
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Hi,

Is it possible to getParent() to get the parent tag from within a tag file? I have a tag that should only be used within a specific parent tag and I want to ensure this somehow. Any ideas?

Thanks,
Gili
 
Tim Holloway
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Well, to be precise, there's a way to chase all the way back up the tag stack in case the enclosed tag isn't the immediate child of the enclosing parent.

As for the exact code, I don't remember, so I'd have to RTFM.

Or you will.
 
Gili Tzabari
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I am not aware of any manual for tag files. What is your source?

Gili
 
Bear Bibeault
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I am not aware of any manual for tag files.


The JSP 2.0 Specification is available from Sun's site.
[ December 21, 2004: Message edited by: Bear Bibeault ]
 
Gili Tzabari
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I just flipped through the specification. It doesn't seem to discuss this matter at all. The only thing that *might* help is that tag files have access to a bunch of implicit variables including JspContext but I don't see how one can use any of them to find the enclosing tag. They all seem to operate on JSP concerns, not tag concerns.

Gili
 
Gili Tzabari
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Anyone have any idea?

Gili
 
Gili Tzabari
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Ben,

I know how to getParent() from within a tag Object, but what I meant is, how do I do the same from witin a tag file (that is .tag and .tagx files)? I can't seem to find a way.

Gili
 
Bear Bibeault
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Considering that scriplets are disallowed in tag files, I suspect that this is not something that was deemed useful.
 
Gili Tzabari
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I don't understand. What does scriptlet support have anything to do with nested classes? That is, if I wanted to implement <if> <else> tags inside a <condition> enclosing tag, why wouldn't I be able to do this using .tagx files?

Gili
 
Bear Bibeault
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Perhaps you could elaborate on exactly what it is you are trying to achieve? A getParent() call isn't going to be available or useful in a scriptless environment. Are you just trying to get access to attributes of the parent tag? Ensure nesting? Other?
 
Gili Tzabari
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I'm trying to ensure nesting: that is, "if" and "else" may only be used within "condition", otherwise throw an exception.

Gili
 
Bear Bibeault
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Then in my opinion you are using a tack hammer where a ball-peen is required.

Tag files are primarily intnded to replace tags whose primary output is pure JSP/HTML -- removing the need to build up HTML in Java code. For the type of processing you are intending you would be better off implementing the tag as a Java class extending either the new "simple" or the "classic" tag support library.

If you do insist on using tag files, I would have the parent tag place information on the page context that the child tags could access and check with JSTL tags.
 
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