Copy node with different attribute or Add child nodes to other node based on condition via XSLT

Question

I'm working on an xslt which will be used to translate a set of xmls files, a sample input xml is something like :-

<?xml version="1.0" encoding="UTF-8"?>  
<bookstore>

  <book id="A12">
    <bookattribute  name="abc"  price="200" />
    <bookattribute  name="xyz"  price="300" />
    <bookattribute  name="pqr"  price="400" />
    <bookattribute  name="lnz"  price="500" />
  </book>

  <book id="B12">
    <bookattribute  name="cpz"  price="300" />
    <bookattribute  name="rts"  price="800" />
  </book>


  <novel id="AA12">
    <bookattribute  name="yps"  price="200" />
    <bookattribute  name="udv"  price="600" />
  </novel>

  <!-- book node with id=AA12 may or may not be present in the xml  -->

  <book id="AA12">
    <bookattribute  name="abc"  price="200" />
    <bookattribute  name="aps"  price="600" /> 
  </book>

</bookstore>

i want to transform it by creating copy of node "book" with attribute id="A12" based on condition that , if node book with attribute id=AA12 does not exist, then create copy of node "book"(attribute id="A12") and in the copy change id to "AA12" (thus its copy of node with change of attribute value), but if node with book(id="AA12") already exists in the xml then add those child nodes of book(id=A12) which are not present in "book"(attribute id="AA12"), Here I want to add only those child nodes(with bookattribute "name" as the key ) which are not present in book@id=AA12) , for example if child node bookattribute name="abc" is already present in book@id=AA12 then it should not be added again to it, further their may be certain other element nodes like novel or ebook which may also have attribute id="AA12" these nodes must be copied as it is.

so output, in case (input file above contains node "book"(attribute id="AA12") )

<bookstore>
            <book id="A12">
                <bookattribute  name="abc"  price="200" />
                <bookattribute  name="xyz"  price="300" />
                <bookattribute  name="pqr"  price="400" />
                <bookattribute  name="lnz"  price="500" />
              </book>

              <book id="B12">
                <bookattribute  name="cpz"  price="300" />
                <bookattribute  name="rts"  price="800" />
              </book>

  <novel id="AA12">
    <bookattribute  name="yps"  price="200" />
    <bookattribute  name="udv"  price="600" />
  </novel>

               <book id="AA12">
                <bookattribute  name=aps  price=600 />
                <bookattribute  name="abc"  price="200" />
                <bookattribute  name="xyz"  price="300" />
                <bookattribute  name="pqr"  price="400" />
                <bookattribute  name="lnz"  price="500" />
              </book>
    </bookstore>

output , in case (input file does not contain node "book"(attribute id="AA12") )

    <bookstore>

                  <book id="A12">
                    <bookattribute  name="abc"  price="200" />
                    <bookattribute  name="xyz"  price="300" />
                    <bookattribute  name="pqr"  price="400" />
                    <bookattribute  name="lnz"  price="500" />
                  </book>

                  <book id="B12">
                    <bookattribute  name="cpz"  price="300" />
                    <bookattribute  name="rts"  price="800" />
                  </book>

 <novel id="AA12">
        <bookattribute  name="yps"  price="200" />
        <bookattribute  name="udv"  price="600" />
      </novel>

                   <book id="AA12">
                    <bookattribute  name="abc"  price="200" />
                    <bookattribute  name="xyz"  price="300" />
                    <bookattribute  name="pqr"  price="400" />
                    <bookattribute  name="lnz"  price="500" />
                  </book>
        </bookstore>

I have been able to create xslt as below which creates copy with changed attributes as required , but im unable to work out addition of child nodes in case node book with id="AA12" exists, any pointers would be helpful

my xslt:-

 <?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:output method="xml"/> <xsl:template match="*"> <xsl:copy> <xsl:copy-of select="@*"/> <xsl:apply-templates/> </xsl:copy> </xsl:template> <xsl:template match="comment()|processing-instruction()"> <xsl:comment> <xsl:value-of select="."/> </xsl:comment> </xsl:template> <xsl:template match="book[@id='A12']"> <xsl:copy> <xsl:attribute name="id">A12</xsl:attribute> <xsl:apply-templates /> </xsl:copy> <xsl:copy> <xsl:attribute name="id">AA12</xsl:attribute> <xsl:apply-templates /> </xsl:copy> </xsl:template> </xsl:stylesheet> 

Answer 1

Please be careful when posting XML, your input document is not well-formed.

Use a key to identify book elements by their ID. Then, the rationale is as follows:

• find the bookstore element and copy it to the output
• inside bookstore , first copy everything from the input document, except the book element where id="AA12"
• then construct a new element <book id="AA12"> in all cases, and copy into it all the children of (potentially) book id="AA12" and book id="A12"

XSLT Stylesheet

EDIT I have edited the stylesheet in response to

this xslt may require minor fix as it may duplicate the child nodes, for example if is already present in book@id="A12" and "AA12", a filter to avoid copying duplicate child nodes would be required

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:output method="xml" omit-xml-declaration="yes" encoding="UTF-8" indent="yes" />

    <xsl:output method="xml" indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:key name="book-by-id" match="book" use="@id"/>

    <xsl:template match="bookstore">
        <xsl:copy>
          <xsl:apply-templates select="@*|node()[not(self::book and @id = 'AA12')]"/>
          <book id="AA12">
              <xsl:copy-of select="key('book-by-id','AA12')/*"/>
              <xsl:for-each select="key('book-by-id','A12')/*">
                  <xsl:if test="not(./@name = key('book-by-id','AA12')/*/@name)">
                      <xsl:copy-of select="."/>
                  </xsl:if>
              </xsl:for-each>
          </book>
      </xsl:copy>
    </xsl:template>

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

</xsl:transform>

Alternative solution:

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:output method="xml" omit-xml-declaration="yes" encoding="UTF-8" indent="yes" />

    <xsl:output method="xml" indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:key name="book-by-id" match="book" use="@id"/>
    <xsl:key name="book-attribute-by-name" match="bookattribute" use="@name"/>

    <xsl:template match="bookstore">
        <xsl:copy>
          <xsl:apply-templates select="@*|node()[not(@id = 'AA12')]"/>
          <book id="AA12">
              <xsl:apply-templates select="key('book-by-id','AA12')/*,key('book-by-id','A12')/*"/>
          </book>
      </xsl:copy>
    </xsl:template>

    <xsl:template match="key('book-by-id','A12')/*[@name = key('book-by-id','AA12')/*/@name]"/>

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

</xsl:transform>

XML Output

In case there already was a book element with id="AA12" :

<bookstore>
   <book id="A12">
      <bookattribute name="abc" price="200"/>
      <bookattribute name="xyz" price="300"/>
      <bookattribute name="pqr" price="400"/>
      <bookattribute name="lnz" price="500"/>
   </book>
   <book id="B12">
      <bookattribute name="cpz" price="300"/>
      <bookattribute name="rts" price="800"/>
   </book>
   <!-- book node with id=AA12 may or may not be present in the xml  -->
   <book id="AA12">
      <bookattribute name="abc" price="200"/>
      <bookattribute name="xyz" price="300"/>
      <bookattribute name="pqr" price="400"/>
      <bookattribute name="lnz" price="500"/>
      <bookattribute name="aps" price="600"/>
   </book>
</bookstore>

In case there was no such element:

<bookstore>
   <book id="A12">
      <bookattribute name="abc" price="200"/>
      <bookattribute name="xyz" price="300"/>
      <bookattribute name="pqr" price="400"/>
      <bookattribute name="lnz" price="500"/>
   </book>
   <book id="B12">
      <bookattribute name="cpz" price="300"/>
      <bookattribute name="rts" price="800"/>
   </book>
   <!-- book node with id=AA12 may or may not be present in the xml  -->
   <book id="AA12">
      <bookattribute name="abc" price="200"/>
      <bookattribute name="xyz" price="300"/>
      <bookattribute name="pqr" price="400"/>
      <bookattribute name="lnz" price="500"/>
   </book>
</bookstore>