CODEWITHSUNDEEP
xsltxpath
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Reputation: 506

XPath filter not working on XSL

I have the following XML

<?xml version="1.0"?>
<people><human><sex>male</sex><naxme>Juanito</naxme>
</human>
<human><sex>female</sex><naxme>Petra</naxme></human>
<human><sex>male</sex><naxme>Anaximandro</naxme></human>
</people>

and this XSL

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="utf-8" indent="no"/>
    <xsl:template match="/people/human[sex='male']">

        <xsl:value-of select="naxme"/>
         </xsl:template>
</xsl:stylesheet>

I'm expecting it to filter out the female, and it kind of works but I get odd values for the non-matching nodes:

Juanito
femalePetra
Anaximandro

I'm expecting the same output as with

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="utf-8" indent="no"/>
    <xsl:template match="/people/human">
<xsl:if test = "sex='male'">
        <xsl:value-of select="naxme"/>
</xsl:if>         </xsl:template>
</xsl:stylesheet>

Thanks!

Upvotes: 0

Views: 474

Answers (2)

user764357
user764357

Reputation:

I'll expand on Daniels answer which covers a little of the why.

The reason you are getting two different outputs comes down to the built-in template rules, and how nodes and text are treated by default.

Summarising that link, if no other template exists, there are default templates that ensure every node - be it element, text, attribute, comment - will be encoutered, just to ensure that other nodes that do have rules can be processed correctly.

With this XSLT:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/people/human[sex='male']">
        <xsl:value-of select="naxme"/>
    </xsl:template>
</xsl:stylesheet>

you have an explicit rule that says:

If you find a node that matches the XPath /people/human[sex='male] do this template.

Along with the default rule:

Find all nodes, and then process all of their children. If it is text, just output the text.

This default rule is why your template is being processed, since you have no explicit rule for the root node - / - it any every child and grandchild node are processed using the default rules, unless another exists. As such, each node is traversed using the defaults, except for the nodes matching /people/human[sex='male]. The result of this is that when you have a node that is "female" the text is being spat out instead of ignored.

However, contrast this with:

<xsl:template match="/people/human">
    <xsl:if test = "sex='male'">
        <xsl:value-of select="naxme"/>
    </xsl:if>
</xsl:template>

Where the rule becomes:

If you find a node that matches the XPath /people/human do this template.

It just so happens that in that template, you have an extra condition that says, if it is male, then process it in some way, with no other conditions, so if a "female" node is encountered it is now blank in the output.

Lastly, the reason why Daniels answer works but could easily break, is that it changes the rule for processing text. Instead of now copying all text as in the default rules, it outputs nothing (as per the empty template. However, if you had any other templates which used xsl:apply-templates to process text and were expecting text, they would also now output nothing.

Upvotes: 3

Daniel Haley
Daniel Haley

Reputation: 52848

It's probably because of XSLT's built-in template rules. Try adding this template:

<xsl:template match="text()"/>

Upvotes: 3

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