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Re: Generating XPath expressions

• From: Eric van der Vlist <vdv@d...>
• To: Sanjay Khattar <sanjaykhattar1@y...>
• Date: Tue, 12 Dec 2000 08:53:49 +0100

Sanjay Khattar wrote:
.../...
> 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>

On this very specific example, yes, and so would "." !

But generally speaking, no it doesn't identify a specific node.

Your instance document could be:

<root>
<elemA>
    <elemB>cdata1</elemB>
</elemA><elemA>
    <elemB>cdata1</elemB>
</elemA>
</root>

in which case ".//elemA[elemB='cdata1']" would identify 2 nodes.

Without some info about the nodes that might be used as identifiers
(through something like a schema or dtd), I can't see how you can
generate a XPath, except using the position of the nodes
"elemA[1]/elemB[5]".

This is not very robust if the document is updated, though.

> 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.

The difference is that the information that you put in RDBMS are highly
structured and that you can access system tables to build queries...

Here also, you'd need "system tables" and a schema could play this role.

Eric
 
> Thanks
> Sanjay
> 
> >
> > However, it would be feasible to construct a minimal
> > path, perhaps
> > using only the parent and child axes.
> >
> > HTHs,
> > Steve Ball
> >
> > --
> > Steve Ball            | waX Me Lyrical XML Editor |
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-- 
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Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
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  • Re: Generating XPath expressions
    • From: Sanjay Khattar <sanjaykhattar1@y...>

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