How to join two XML files with a matching node

Question

I need to find a way to join two XML files when they have a matching node. From what I gather this could be accomplished with many different languages... is there a PHP or an AJAX way to do this? From other posts on SO I see XSLT solutions.. that I dont really get. Is this the best/preferred method? If so, know of any helpful XSLT tutorials?

For example XML-1 is like :

<FOO>
    </A>
    </B>
    </C>
    </D>
</FOO>

and XML-2 :

<FOO>    
    </B>
    </E>
</FOO>

What would be the best approach for checking where <B>==<B> then add <E>

Update

Well I cant get this to work with my hypothetical example and thought I would update with what I am really doing to see if anyone can help me figure this. I have tried the methods from below and others I have found on SO with no luck.

The real schema is like :

file1.xml

<?xml version="1.0"?>
<DATA>
  <ITEM>
    <PRODUCT_TYPE>simple</PRODUCT_TYPE>
    <STYLE_COLOR>1524740007</STYLE_COLOR>
    <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
    <CLASS_NAME>FOOTWEAR</CLASS_NAME>
    <STATUS>Disabled</STATUS>
  </ITEM>
 ...
</DATA>

file2.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="merge.xsl" ?>
<DATA>
  <ITEM>
    <STYLE_COLOR>1524740007</STYLE_COLOR>
    <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
  </ITEM>
  ....
</DATA>

What I need to figure out is to have a new XML file generated that would merge these nodes with identical SYTLE_COLOR and look like:

<DATA>
  <ITEM>
    <PRODUCT_TYPE>simple</PRODUCT_TYPE>
    <STYLE_COLOR>1524740007</STYLE_COLOR>
    <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
    <CLASS_NAME>FOOTWEAR</CLASS_NAME>
    <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
    <STATUS>Disabled</STATUS>
  </ITEM>

I tried creating a merge.xsl that looks like :

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="ISO-8859-1" indent="yes" />
  <xsl:output indent="yes"/>
  <xsl:variable name="with" select="'file-2.xml'" />
  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()" />
    </xsl:copy>
  </xsl:template>

  <xsl:template match="scene">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()" />
      <xsl:variable name="info" select="document($with)/DATA/ITEM[STYLE_COLOR=current()/STYLE_COLOR]/." />
      <xsl:for-each select="$info/*">
        <xsl:if test="name()!='STYLE_COLOR'">
          <xsl:copy-of select="." />
        </xsl:if>
      </xsl:for-each>
    </xsl:copy>
  </xsl:template>
</xsl:transform>

I also tried a merge like this:

<xsl:stylesheet version="1.0" 
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output indent="yes"/>
    <xsl:variable name="input2" select="document('file-2.xml')/DATA/ITEM"/>
    <xsl:template match="STYLE_COLOR">
        <xsl:copy>
            <xsl:apply-templates select="*"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="*">
        <xsl:choose>
            <xsl:when test="$input2/*[name()=name(current())]">
                <xsl:copy-of select="$input2/*"/>
            </xsl:when>
            <xsl:otherwise>
                <xsl:copy-of select="."/>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>
</xsl:stylesheet> 

Neither of these methods are working.. sorry XSLT is very new to me so I am not sure what I am doing and would really appreciate some hand holding on this one.

Answer 1

This is the original transform slightly modified to adapt the new requirements. The merge is performed by checking against file2.xml elements. For the current ITEM in file1, a children ITEM in file2 will be merged only if not present in the file1.

---

[XSLT 1.0]

<xsl:stylesheet version="1.0" 
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

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

    <xsl:variable name="input2" select="document('test_input2.xml')/DATA"/>

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

    <xsl:template match="ITEM">
        <xsl:variable name="item" select="
            $input2/ITEM[STYLE_COLOR=current()/STYLE_COLOR]"/>
        <xsl:variable name="ITEM" select="."/>

        <xsl:if test="$item">
            <xsl:copy>

                <xsl:for-each select="$item/*">
                    <xsl:if test="count($ITEM/*[name()=name(current())])=0">
                        <xsl:copy-of select="." />
                    </xsl:if>
                </xsl:for-each>

                <xsl:apply-templates select="*"/>
            </xsl:copy>
        </xsl:if>
    </xsl:template>

</xsl:stylesheet> 

Applied on this input1.xml:

<DATA>
  <ITEM>
    <PRODUCT_TYPE>simple</PRODUCT_TYPE>
    <STYLE_COLOR>1524740007</STYLE_COLOR>
    <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
    <CLASS_NAME>FOOTWEAR</CLASS_NAME>
    <STATUS>Disabled</STATUS>
  </ITEM>
  <ITEM>
    <PRODUCT_TYPE>simple</PRODUCT_TYPE>
    <STYLE_COLOR>1524740008</STYLE_COLOR>
    <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
    <CLASS_NAME>FOOTWEAR</CLASS_NAME>
    <STATUS>Disabled</STATUS>
  </ITEM>
  <ITEM>
    <PRODUCT_TYPE>simple</PRODUCT_TYPE>
    <STYLE_COLOR>777</STYLE_COLOR>
    <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
    <CLASS_NAME>FOOTWEAR</CLASS_NAME>
    <STATUS>Disabled</STATUS>
  </ITEM>
</DATA>

and input2.xml to merge, produces:

<DATA>
  <ITEM>
    <STYLE_COLOR>1524740007</STYLE_COLOR>
    <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
    <CLASS_NAME>XXX</CLASS_NAME>
    <OTHER>YYY</OTHER>
  </ITEM>
  <ITEM>
    <STYLE_COLOR>1524740008</STYLE_COLOR>
    <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
  </ITEM>
</DATA>

produces:

<DATA>
   <ITEM>
      <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
      <OTHER>YYY</OTHER>
      <PRODUCT_TYPE>simple</PRODUCT_TYPE>
      <STYLE_COLOR>1524740007</STYLE_COLOR>
      <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
      <CLASS_NAME>FOOTWEAR</CLASS_NAME>
      <STATUS>Disabled</STATUS>
   </ITEM>
   <ITEM>
      <NEXT_ARRIVAL>2011-08-05</NEXT_ARRIVAL>
      <PRODUCT_TYPE>simple</PRODUCT_TYPE>
      <STYLE_COLOR>1524740008</STYLE_COLOR>
      <SHORT_DESCRIPTION>Black Shoe</SHORT_DESCRIPTION>
      <CLASS_NAME>FOOTWEAR</CLASS_NAME>
      <STATUS>Disabled</STATUS>
   </ITEM>
</DATA>

Notice that:

• the transform does not override existing elements for a given ITEM, just copy the missing ones
• ITEM in input1.xml is copied in output only if has a match in input2.xml