XSLT help - XSL for various similar XML, Template usage - templates

Question

I am very new to XSL and XPath. Apologies if this question shows some stupidity.
I have an XML something like
<root>
<widget name="status">
...
<component name="date">
<component name="day" label="Fri"/>
<component name="date" label="4"/>
</component>
<component name="time" label="11:23 AM"/>
....
</widget>
<widget name="foo">
</widget>
</root>
I need to create a DateTime tag which is compose of all the three values something like
Fri 4 11:23 AM
I am writing an XSL for it.
<DateTime>
<xsl:value-of select="(//widget[#name="status"]/component[#name='date'])[1]/#label"/>
<xsl:text> </xsl:text>
<xsl:value-of select="(//widget[#name="status"]/component[#name='date'])[2]/#label"/>
<xsl:text> </xsl:text>
<xsl:value-of select="//widget[#name="status"]/component[#name='time']/#label"/>
</DateTime>
Question:
I am passing the "widget[#name="date"]" to each of the select statement. Is there any better way to shorten the xpath.
I need to move this into a template and call the template. which one I should use call-template/apply-templates?
We have a set of similar applications which generate these XML. The above XML is from applicationA. ApplicationB might show the detail in little bit different way, something like <component name="datetime">Fri 4 11:23 AM</component>. We have almost 3-4 such application where they display the details in little bit different way.
DateTime is just an example, there are some other details which I also need to capture from these various applications.
I am thinking to write a single XSL to deal with all the applications.

Answer 1

One way to do it with your XML would be this:
<xsl:template match="widget">
<!-- ... -->
<xsl:apply-templates select="." mode="create-date-time" />
<!-- ... -->
</xsl:template>
<xsl:template match="widget" mode="create-date-time">
<xsl:variable name="date" select="component[#name='date']" />
<xsl:variable name="time" select="component[#name='time']" />
<DateTime>
<xsl:value-of select="normalize-space(
concat(
$date/component[#name='day']/#label, ' ',
$date/component[#name='date']/#label, ' ',
$time/#label
)
)" />
</DateTime>
</xsl:template>
I am passing the widget[#name="date"] to each of the select statement. Is there any better way to shorten the xpath.
Use <xsl:template>/<xsl:apply-templates>, and relative paths. Store things you need more than once in an <xsl:variable>. See above.
I need to move this into a template and call the template. which one I should use call-template/apply-templates?
The latter. Always go for <xsl:apply-templates> unless there is good reason not to. As a rule of thumb: If you are unsure, then there is no good reason.
We have a set of similar applications which generate these XML. The above XML is from applicationA. ApplicationB might show the detail in little bit different way, something like <component name="datetime">Fri 4 11:23 AM</component> We have almost 3-4 such application where they display the details in little bit different way.
You could expand the create-date-time template to accommodate for this:
<xsl:template match="widget" mode="create-date-time">
<xsl:variable name="date" select="component[#name='date']" />
<xsl:variable name="time" select="component[#name='time']" />
<xsl:variable name="dt" select="component[#name='datetime']" />
<DateTime>
<xsl:value-of select="normalize-space(
concat(
$dt/label, ' ',
$date/component[#name='day']/#label, ' ',
$date/component[#name='date']/#label, ' ',
$time/#label
)
)" />
</DateTime>
</xsl:template>
There will be no error if certain components are missing. normalize-space() makes sure that there are no excess spaces for any combination of components.
The above may fail if the date+time and datetime components are not mutually exclusive (I've assumed they are). If they are not, or if more complicated cases occur, create additional specific templates, like this one:
<xsl:template match="widget[component[name='datetime']]" mode="create-date-time">
<xsl:variable name="dt" select="component[#name='datetime']" />
<DateTime>
<xsl:value-of select="component[#name='datetime']/#label" />
</DateTime>
</xsl:template>
The <xsl:apply-templates> will make sure the correct one is called. Just create specific match= expressions for each case that can occur.

Answer 2

This simple transformation (16 lines, single template, completely "push" style, no variables, no modes):
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match=
"component
[contains('|day|date|time|',
concat('|', #name, '|'))
]
">
<xsl:value-of select="concat(#label, ' ')"/>
<xsl:apply-templates/>
</xsl:template>
<xsl:template match="text()"/>
</xsl:stylesheet>
when applied on the provided XML document:
<root>
<widget name="status">
...
<component name="date">
<component name="day" label="Fri"/>
<component name="date" label="4"/>
</component>
<component name="time" label="11:23 AM"/>
....
</widget>
<widget name="foo">
</widget>
</root>
produces exactly the wanted result:
Fri 4 11:23 AM