Xpath query to select all elements ignoring descendants based on criteria - xpath

Question

I am trying to select all the <set>erase</set> elements such that if two or more elements have the <set>erase</set> in hierarchy (Ex: <b> and <d> both have <set>erase</set>) then only the element in parent node name has to be selected(ie <b> in this case).
Sample xml below:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<a>
<b>
<set>erase</set>
<d>
<set>erase</set>
</d>
</b>
<c>
<x></x>
</c>
<e>
<y>
<set>erase</set>
<q></q>
</y>
<z>
<p>
<set>erase</set>
</p>
</z>
</e>
</a>
When I use the query = //set[contains(.,'erase')] I get all <set>erase</set> of nodesList b,d,y,p in result set.
I need help in framing the query to select <set>erase</set> of b , y and p.

Answer 1

Here is the same solution:
One XPath expression that selects exactly the wanted elements is:
//*[set[. = 'erase' and not(node()[2])]
and
not(ancestor::*
[set
[. = 'erase' and not(node()[2])]
]
)
]
XSLT - based verification:
<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="/">
<xsl:for-each select=
"//*[set[. = 'erase' and not(node()[2])]
and
not(ancestor::*
[set
[. = 'erase' and not(node()[2])]
]
)
]">
<xsl:value-of select="name()"/>
<xsl:text>
</xsl:text>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
when this transformation is applied on the provided XML document:
<a>
<b>
<set>erase</set>
<d>
<set>erase</set>
</d>
</b>
<c>
<x></x>
</c>
<e>
<y>
<set>erase</set>
<q></q>
</y>
<z>
<p>
<set>erase</set>
</p>
</z>
</e>
</a>
The contained XPath expression is evaluated and the names of the selected elements are output -- correctly and as expected:
b
y
p
If you need to select the set children of the selected above elements, just append the above XPath expression with /set:
//*[set[. = 'erase' and not(node()[2])]
and
not(ancestor::*
[set
[. = 'erase' and not(node()[2])]
]
)
]
/set
Again, XSLT - based verification:
<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="/">
<xsl:copy-of select=
"//*[set[. = 'erase' and not(node()[2])]
and
not(ancestor::*
[set
[. = 'erase' and not(node()[2])]
]
)
]
/set
"/>
</xsl:template>
</xsl:stylesheet>
This transformation just evaluates the above XPath expression and copies to the output the correctly selected three set elements:
<set>erase</set>
<set>erase</set>
<set>erase</set>