Question

I’m new to XSLT, and am having problems merging node lists. Would appreciate your help with the following scenario:

Input:

>       <A Id="1">
>         <B Id="4">
>           <Attr>
>             <someAttr1>2</someAttr1>
>             <someAttr2>1</someAttr2>
>           </Attr>
>           <C Id="7">
>             <Attr>
>              <someAttr3>2</someAttr3>
>              <someAttr4>1</someAttr4>
>              <someAttr5>7</someAttr5>
>             </Attr>
>           </C>
>         </B>
>         <B Id="9">
>           <Attr>
>             <someAttr1>6</someAttr1>
>             <someAttr2>0</someAttr2>
>           </Attr>
>           <C Id="11">
>             <Attr>
>              <someAttr3>1</someAttr3>
>              <someAttr4>3</someAttr4>
>              <someAttr5>5</someAttr5>
>             </Attr>
>           </C>
>         </B>
>       </A>

Output:

  <A Id="1">
    <B Id="4">
      <Attr>
        <someAttr1>2</someAttr1>
        <someAttr2>1</someAttr2>
        <someAttr3>2</someAttr3>
        <someAttr4>1</someAttr4>
        <someAttr5>7</someAttr5>
      </Attr>
    </B>
    <B Id="9">
      <Attr>
        <someAttr1>6</someAttr1>
        <someAttr2>0</someAttr2>
        <someAttr3>1</someAttr3>
        <someAttr4>3</someAttr4>
        <someAttr5>5</someAttr5>
      </Attr>
    </B>
  </A>

Answer 1

It looks like you want to combine all Attr elements that occur at any level under a B element.

First, you would need a template to match B elements with Attr elements

<xsl:template match="B[Attr]">

And in the template, you would create an Attr element, and copy all descendant elements under the Attr elements

<Attr>
   <xsl:copy-of select=".//Attr/*" />
</Attr>

Here is the full XSLT

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   <xsl:output method="xml" indent="yes"/>

   <xsl:template match="B[Attr]">
      <B>
         <xsl:apply-templates select="@*"/>
         <Attr>
            <xsl:copy-of select=".//Attr/*" />
         </Attr>
      </B>
   </xsl:template>

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

When applied to your sample XML, the following is output

<A Id="1">
   <B Id="4">
      <Attr>
         <someAttr1>2</someAttr1>
         <someAttr2>1</someAttr2>
         <someAttr3>2</someAttr3>
         <someAttr4>1</someAttr4>
         <someAttr5>7</someAttr5>
      </Attr>
   </B>
   <B Id="9">
      <Attr>
         <someAttr1>6</someAttr1>
         <someAttr2>0</someAttr2>
         <someAttr3>1</someAttr3>
         <someAttr4>3</someAttr4>
         <someAttr5>5</someAttr5>
      </Attr>
   </B>
</A>