xml-dev - Re: Generating XPath expressions

[Sanjay Khattar <sanjaykhattar1@yahoo.com>]

--- Steve Ball <Steve.Ball@zveno.com> wrote:
> "Khattar, Sanjay" wrote:
> > 
> > Does anyone here know of a quick way to generate
> an XPath expression like
> > 'elemA[elemB='cdata1']' from an xml node instance
> like
> > <elemA>
> >     <elemB>cdata1</elemB>
> > </elemA>
> > 
> > Of course, the node instance could be of arbitrary
> complexity.
> 
> I can't imagine that a general-purpose library could
> guess
> at the user's intention, as your example seems to
> indicate is
> required.  In this example, what is the context,
> what is to be
> selected and how much of the surrounding context is
> to be
> considered?
> 
> Perhaps what you want is:
> 
> given a context (DOM) node and a target (DOM) node,
> construct an XPath 
> which will select the target from the context.

Exactly. That's what I want. 

> 
> My initial thought is that in general there are many
> solutions for
> any given context and target nodes.  In fact, the
> solution set is
> most likely unbounded.

Now is it? Given a context node 
<elemA>
    <elemB>cdata1</elemB>
</elemA>

and a target node
<elemA>
    <elemB>cdata1</elemB>
</elemA>

how many XPath expressions can one create? Even if one
can, wouldn't an XPath like './/elemA[elemB='cdata1']'
search for this particular node alone in any xml doc:
<elemA>
    <elemB>cdata1</elemB>
</elemA>

I'd say that this sounds to me something like a SQL
Query Builder - I'd love to know if I am being too
fanciful here.

Thanks
Sanjay

> 
> However, it would be feasible to construct a minimal
> path, perhaps
> using only the parent and child axes.
> 
> HTHs,
> Steve Ball
> 
> -- 
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