Re: [xsl] Fetching the value of a dynamically assigned attribute

["Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

> On 19 Jul 2017, at 00:52, Joseph L. Casale jcasale@xxxxxxxxxxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> While mocking up some examples related to a previous question,
> I have an example where I add a namespace to my stylesheet and
> add some data to it:
>
>  <myns:data>
>    <foo>
>      <bar>one</bar>
>      <bar>two</bar>
>      <bar>three</bar>
>    </foo>
>  </myns:data>
>
> I also load another XML doc I am using data from:
>
>  <xsl:variable name="documentAppConfig"
select="document('some_binary.exe.config')" />
>
> While looping over the elements from the data I added to my stylesheet, I
> am trying to select the value of an attribute where the attribute name is
> dynamically specified:
>
>    <xsl:for-each select="document('')/xsl:stylesheet/myns:data/foo/bar">
>
>        <!-- this works: -->
>        <xsl:value-of select="concat('some-text', text())" />

Better is <xsl:value-of select="concat('some-text', .)" /> - because the first
one will fail if there are multiple text nodes separated by comments. Using
"." here is equivalent to string(.) which gives you the string-value of the
element.
>
>
>        <!-- this does not work: -->
>        <xsl:value-of
select="$documentAppConfig/configuration/myNode/@*[local-name()=text()]" />

That's because within the predicate the context item is an attribute node, and
attribute nodes don't have text node children. But you couldn't use "." here
either, because the context is wrong. You could use "current()" however.
>
>        <!-- this works: -->
>        <xsl:variable name="text" select="text()" />
>        <xsl:value-of
select="$documentAppConfig/configuration/myNode/@*[local-name()=$text]" />
>
>    </xsl:for-each>
>
> That result is not surprising, but what is the syntactically correct
> way of accomplishing this, or is the intermediate assignment the only
> way?
>
These are all syntactically correct, but the one that doesn't work is
semantically incorrect, because you didn't take context into account.

Michael Kay
Saxonica