Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx> wrote:
> [...]
>>> I would like to get "unit", but I just get an empty array ({}).
>>> How can I get "unit" ?
>> AFAIK, this is not related to PostgreSQL, but inherent to
>> XPath in that it returns elements from the document that
>> fulfill the XPath expression *unchanged*.
> My (poor) understanding is that XPath can be used as an
> expression language and as a selector specifier language.
> You can observe this in XSLT, where
> <xsl:template match="some-xpath"/>
> uses XPath as a selector of elements, and:
> <xsl:value-of select="some-xpath"/>
> uses XPath as an expression language, returning the output
> of a given XPath expression or function not just the
> "matched"/"not matched" status.
> I found this very confusing myself when learning XSLT, and
> it's possible I'm still misunderstanding it somewhat, but
> it's clear that XPath can be used in more than one way.
> [...]
Okay, that's maybe due to my XML socialization: An XPath ex-
pression to me has always been something you use in
"xsl:template" and "xmllint --shell", as in "xsl:value-of" &
Co. you have also access to other functions. It's even in
the specification :-):
| [...] The primary purpose
| of XPath is to address parts of an XML [XML] document. [...]
(from: <URI:http://www.w3.org/TR/xpath/>)
Tim
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