Get distinct values within specific attributes

问题

I've got the following XML Code:

<!-- language: xml -->
<Stats>
  <Stat>
    <Data Name="Value">63.76</Data>
    <Data Name="Entity">first</Data>
  </Stat>
  <Stat>
    <Data Name="Value">51.23</Data>
    <Data Name="Entity">second</Data>
  </Stat>
  <Stat>
    <Data Name="Value">46.1</Data>
    <Data Name="Entity">third</Data>
  </Stat>
  <Stat>
    <Data Name="Value">61.21</Data>
    <Data Name="Entity">first</Data>
  </Stat>
</Stats>

I want to filter only where 'Data[@Name='Entity']. Using xpath: /Stats/Stat/Data[@Name="Entity"] returns: first second third first

But I want the results to be unique. So I only get: first second third

EDIT: I need this to work for xpath version 1.0.

回答1:

Use this XPath 1.0 expression:

/Stats/Stat
   [Data/@Name='Entity'
  and
   not(Data[@Name='Entity']  = following-sibling::Stat/Data[@Name = 'Entity'])
   ]
    /Data[@Name='Entity']

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=
      "/Stats/Stat
           [Data/@Name='Entity'
          and
           not(Data[@Name='Entity']  = following-sibling::Stat/Data[@Name = 'Entity'])
           ]
            /Data[@Name='Entity']
      "/>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the following XML document (produced by correcting the non-well-formed provided text):

<Stats>
  <Stat>
    <Data Name="Value">63.76</Data>
    <Data Name="Entity">first</Data>
  </Stat>
  <Stat>
    <Data Name="Value">51.23</Data>
    <Data Name="Entity">second</Data>
  </Stat>
  <Stat>
    <Data Name="Value">46.1</Data>
    <Data Name="Entity">third</Data>
  </Stat>
  <Stat>
    <Data Name="Value">61.21</Data>
    <Data Name="Entity">first</Data>
  </Stat>
</Stats>

the above XPath expression is evaluated and the selected nodes are copied to the output:

<Data Name="Entity">second</Data>
<Data Name="Entity">third</Data>
<Data Name="Entity">first</Data>

Note: If you just need the text nodes ("first", "second" and "third"), just use this single XPath expression:

/Stats/Stat
   [Data/@Name='Entity'
  and
   not(Data[@Name='Entity']  = following-sibling::Stat/Data[@Name = 'Entity'])
   ]
    /Data[@Name='Entity']
      /text()

回答2:

You need to say which version of XPath. In XPath 2.0, it's trivial:

distinct-values(/Stats/Stat/Data/@Name)

来源：https://stackoverflow.com/questions/10532657/get-distinct-values-within-specific-attributes

标签

xml

xpath

distinct