XSLT transforming an xml

Question

I am new to xsl. I want to transform an xml from,

<result name="response" numFound="1" start="0">
  <doc>
    <str name="q">what</str>
    <arr name="suggestion">
                <str>what1</str>
                <str>what2</str>
   </arr>
  </doc>
</result>

to,

<result name="response" numFound="2" start="0">
  <doc>
    <str name="q">what</str>
    <str name="suggestion">what1</str>
  </doc>
  <doc>
    <str name="q">what</str>
    <str name="suggestion">what2</str>
  </doc>
</result>

I could extract the texts, "what1" and "what2" using,

<xsl:template match="/response/result[@name='response']">
             <xsl:for-each select="./doc/arr[@name='suggestion']/str">
                    <xsl:value-of select="normalize-space(.)"/>
                    <xsl:value-of select="$endl"/>
             </xsl:for-each>
    </xsl:template>

But I don't know how to enclose the same into output xml format. Can anyone please help...

Additional feature:

Can anyone please tell if I could add a field to the output doc called <float name="score"> which would get incremented by 100 with each doc?

eg) output:

   <response>
      <lst name="responseHeader">
        <int name="status">0</int>
        <int name="QTime">1</int>
        <lst name="params">
          <str name="indent">on</str>
          <str name="q">"what"</str>
        </lst>
      </lst>
      <result numFound="2" name="response" start="0">
        <doc>
          <str name="query">what</str>
          <str>what1</str>
          <float name="score">100</float>
        </doc>
        <doc>
          <str name="query">what</str>
          <str>what2</str>
          <float name="score">200</float>
        </doc>
        <doc>
          <str name="query">what</str>
          <str>what3</str>
          <float name="score">300</float>
        </doc>
      </result>
    </response>

Can you please tell what function do I suppose to use?

Answer 1

The following stylesheet produces the desired result from your input. It might be too lenient or too strict, but since I don't know your exact requirements or have a schema for the input, it's a best effort. Please use this as a starting point but do proper testing and investigate the meaning of what I provide.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

    <xsl:template match="/*">
        <xsl:copy>
            <xsl:copy-of select="@*" />
            <xsl:attribute name="numFound"><xsl:value-of select="count(doc/arr[@name='suggestion']/str)" /></xsl:attribute>
            <xsl:apply-templates select="doc/arr[@name='suggestion']" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="arr[@name='suggestion']">
        <xsl:for-each select="str">
            <doc>
                <xsl:copy-of select="parent::node()/preceding-sibling:: str[@name='q']" />
                <xsl:variable name="nameAttributeValue" select="parent::node()/@name" />
                <xsl:element name="str"><xsl:attribute name="name"><xsl:value-of select="$nameAttributeValue" /></xsl:attribute><xsl:value-of select="." /></xsl:element>
            </doc>
        </xsl:for-each>
    </xsl:template> 

</xsl:stylesheet>

EDIT: In response to your comment: notice how my first template matches on /*. This comes down to "any root element". If an XPath expression starts with a single /, it's always relative to the document root. If it starts with a double // it basically means anywhere in the current node. If it doesn't start with a slash, it's relative to the current node.

In order to process the XML as in your comment, you'd need to change the stylesheet to...

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

    <xsl:template match="node() | @*">
        <xsl:apply-templates select="node() | @*" />
    </xsl:template>

    <xsl:template match="/response/result">
        <xsl:copy>
            <xsl:copy-of select="@*" />
            <xsl:attribute name="numFound"><xsl:value-of select="count(doc/arr[@name='suggestion']/str)" /></xsl:attribute>
            <xsl:apply-templates select="doc/arr[@name='suggestion']" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="arr[@name='suggestion']">
        <xsl:for-each select="str">
            <doc>
                <xsl:copy-of select="parent::node()/preceding-sibling:: str[@name='q']" />
                <xsl:variable name="nameAttributeValue" select="parent::node()/@name" />
                <xsl:element name="str"><xsl:attribute name="name"><xsl:value-of select="$nameAttributeValue" /></xsl:attribute><xsl:value-of select="." /></xsl:element>
            </doc>
        </xsl:for-each>
    </xsl:template> 

</xsl:stylesheet>

That first template I added is to make sure we override some default template hidden in XSLT. Mind that this will only provide correct output if there's only a single result element in response.

Like I stated, please learn the use of XSLT and XPath expressions to make sure you understand what's going on in the stylesheet.

Answer 2

Here is a solution to the OP's comment that updates the question:

This transformation:

<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="node()|@*">
     <xsl:copy>
       <xsl:apply-templates select="node()|@*"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match="result">
  <result numFound="{count(doc/arr/str)}">
   <xsl:apply-templates select="@*[not(name()='numFound')]"/>
   <xsl:apply-templates/>
  </result>
 </xsl:template>

 <xsl:template match="arr[@name='suggestion']/str">
  <doc>
    <xsl:copy-of select="../../str"/>
    <xsl:copy-of select="."/>
  </doc>
 </xsl:template>

 <xsl:template match="doc|doc/arr">
  <xsl:apply-templates/>
 </xsl:template>
 <xsl:template match="doc/str "/>
</xsl:stylesheet>

when applied on the following (provided in the OP's comment) XML document:

<response>
    <lst name="responseHeader">
        <int name="status">0</int>
        <int name="QTime">1</int>
        <lst name="params">
            <str name="indent">on</str>
            <str name="q">"what"</str>
        </lst>
    </lst>
    <result name="response" numFound="1" start="0">
        <doc>
            <str name="q">what</str>
            <arr name="suggestion">
                <str>what1</str>
                <str>what2</str>
            </arr>
        </doc>
    </result>
</response>

produces the wanted, correct result:

<response>
   <lst name="responseHeader">
      <int name="status">0</int>
      <int name="QTime">1</int>
      <lst name="params">
         <str name="indent">on</str>
         <str name="q">"what"</str>
      </lst>
   </lst>
   <result numFound="2" name="response" start="0">
      <doc>
         <str name="q">what</str>
         <str>what1</str>
      </doc>
      <doc>
         <str name="q">what</str>
         <str>what2</str>
      </doc>
   </result>
</response>

Update:

In an update to his question, the OP requested:

Can anyone please tell if I could add a field to the output doc called <float name="score"> which would get incremented by 100 with each doc?

This is extremely easy to achieve. We add just three lines of code to the existing transformation:

<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="node()|@*">
    <xsl:copy>
        <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
 </xsl:template>

 <xsl:template match="result">
    <result numFound="{count(doc/arr/str)}">
        <xsl:apply-templates select="@*[not(name()='numFound')]"/>
        <xsl:apply-templates/>
    </result>
 </xsl:template>

 <xsl:template match="arr[@name='suggestion']/str">
    <doc>
        <xsl:copy-of select="../../str"/>
        <xsl:copy-of select="."/>
        <float name="score">
         <xsl:value-of select="100*position()"/>
        </float>    
    </doc>
 </xsl:template>

 <xsl:template match="doc|doc/arr">
    <xsl:apply-templates/>
 </xsl:template>
 <xsl:template match="doc/str "/>
</xsl:stylesheet>

When this transformation is applied to this XML document:

<response>
    <lst name="responseHeader">
        <int name="status">0</int>
        <int name="QTime">1</int>
        <lst name="params">
            <str name="indent">on</str>
            <str name="q">"what"</str>
        </lst>
    </lst>
    <result name="response" numFound="1" start="0">
        <doc>
            <str name="q">what</str>
            <arr name="suggestion">
                <str>what1</str>
                <str>what2</str>
                <str>what3</str>
            </arr>
        </doc>
    </result>
</response>

the wanted, correct result is produced:

<response>
   <lst name="responseHeader">
      <int name="status">0</int>
      <int name="QTime">1</int>
      <lst name="params">
         <str name="indent">on</str>
         <str name="q">"what"</str>
      </lst>
   </lst>
   <result numFound="3" name="response" start="0">
      <doc>
         <str name="q">what</str>
         <str>what1</str>
         <float name="score">100</float>
      </doc>
      <doc>
         <str name="q">what</str>
         <str>what2</str>
         <float name="score">200</float>
      </doc>
      <doc>
         <str name="q">what</str>
         <str>what3</str>
         <float name="score">300</float>
      </doc>
   </result>
</response>