[XSLT] How to establish a context node without <xsl:for-each>

[Hoi Wong]

I have an XSLT script collection that converts messed up XML to usuable XML.
Instead of generic template matching, I want to establish a context node for
some branches so that I don't have to rely on absolute path. Here's a
simplified version of my work:


[root.xsl]:
<xsl:include href="common.xsl"/>

<xsl:template match="/">
<patientDisk>
<xsl:call-template name="patientData"/>
</patientDisk>
</xsl:template>

==================================

[patientData.xsl]:

<xsl:template name="patientData">
<birthyear>
<xsl:value-of
select="document('rpt_pat.xml')//parameter[@name='PatientBirthYear']"/>
</birthyear>
<gender>
<xsl:value-of
select="document('rpt_pat.xml')//parameter[@name='PatientGender]"/>
</gender>
</xsl:template>


Instead of specifying document('rpt_pat.xml') every time using absolute
paths, I could have used <xsl:for-each select=document('rpt_pat.xml')>.
However, I'd like to avoid using this syntax because there's only one
instance of document('rpt_pat.xml') node. Using <xsl:for-each> can lead to
whoever that reads my XSLT scripts into thinking that there are multiple
instances of the document('rpt_pat.xml') node, adding confusion to the
already huge chaos.

I'd like to avoid <xsl:template match="(something)"> because some tags have
the same names in the messy XML files that I'm trying to parse, and they can
be distinguished only by observing the hieracy (which branch that XML tag is
under).

Can anybody suggest a neat way to do that? Thanks in advance.

-- Hoi

 

[Martin Honnen]

<xsl:template name="patientData">
<birthyear>
<xsl:value-of
select="document('rpt_pat.xml')//parameter[@name='PatientBirthYear']"/>
</birthyear>
<gender>
<xsl:value-of
select="document('rpt_pat.xml')//parameter[@name='PatientGender]"/>
</gender>
</xsl:template>


Instead of specifying document('rpt_pat.xml') every time using absolute
paths, I could have used <xsl:for-each select=document('rpt_pat.xml')>.
However, I'd like to avoid using this syntax because there's only one
instance of document('rpt_pat.xml') node. Using <xsl:for-each> can lead to
whoever that reads my XSLT scripts into thinking that there are multiple
instances of the document('rpt_pat.xml') node, adding confusion to the
already huge chaos.

I don't think there is a way to change the current node without using
apply-templates or for-each. If you want to shorten the code then using
a variable could do e.g.


<xsl:template name="patientData">
<xsl:variable name="pat_doc" select="document('rpt_pat.xml')"/>
<birthyear>
<xsl:value-of
select="$pat_doc//parameter[@name='PatientBirthYear']"/>
</birthyear>
<gender>
<xsl:value-of
select="$pat_doc//parameter[@name='PatientGender]"/>
</gender>
</xsl:template>

 

[Richard Tobin]

Instead of specifying document('rpt_pat.xml') every time using absolute
paths, I could have used <xsl:for-each select=document('rpt_pat.xml')>.
However, I'd like to avoid using this syntax because there's only one
instance of document('rpt_pat.xml') node. Using <xsl:for-each> can lead to
whoever that reads my XSLT scripts into thinking that there are multiple
instances of the document('rpt_pat.xml') node, adding confusion to the
already huge chaos.

Apply-templates and for-each are the only constructs that let you change
the context node.

I recommend using for-each with a comment to indicate that its only
purpose is to set the context.

-- Richard

 

[David Carlisle]

Instead of specifying document('rpt_pat.xml') every time using absolute
paths,

as others have said you can't change the current node without for-each
or apply-templates, etc, however you could use a variable
<xsl:variable name="rpt" select="document('rpt_pat.xml')"/>
then you can use $rpt///parameter[@name='PatientBirthYear']

In xslt2 I'd do
<xsl:variable name="rpt" select="document('rpt_pat.xml')"/>
<xsl:key name="rpt" match="parameter" use="@name"/>
then


<xsl:template name="patientData">
<birthyear>
<xsl:value-of select="key('rpt','PatientBirthYear',$rpt)"/>
</birthyear>
<gender>
<xsl:value-of select="key('rpt','PatientGender',$rpt)"/>
</gender>
</xsl:template>

The third argument of key doesn't exactly change the current node but it
changes the effective node used for determing the key lookup, which has
more or less the same effect here.

David

 

[Hoi Wong]

Instead of specifying document('rpt_pat.xml') every time using absolute
paths,

as others have said you can't change the current node without for-each or
apply-templates, etc, however you could use a variable
<xsl:variable name="rpt" select="document('rpt_pat.xml')"/>
then you can use $rpt///parameter[@name='PatientBirthYear']

In xslt2 I'd do
<xsl:variable name="rpt" select="document('rpt_pat.xml')"/>
<xsl:key name="rpt" match="parameter" use="@name"/>
then


<xsl:template name="patientData">
<birthyear>
<xsl:value-of select="key('rpt','PatientBirthYear',$rpt)"/>
</birthyear>
<gender>
<xsl:value-of select="key('rpt','PatientGender',$rpt)"/>
</gender>
</xsl:template>

The third argument of key doesn't exactly change the current node but it
changes the effective node used for determing the key lookup, which has
more or less the same effect here.

David

Thanks for the hint.

Unfortunately, the software that I'm using (namely MATLAB and the orphaned
proprietary data converter from the vendor) only support XSLT 1.0.

In fact, I was using the variables trick before hitting this forum so I'll
stick to that because it's easier to debug than switching nodes.

Cheers,
Hoi