Question

I want to merge two files A.xml and map.xml with “Node” elements according to the following rule (nodes are distinguished by @Name):

1. If the element in map.xml has a Src attribute, the element from map should be copied to output
2. If the element exists in A and map and does NOT have @Src, it should be copied from A
3. If the element exists in A but not in map, it should be ignored (with warning)
4. If the element exists in map but not in A, the (empty) element shall be generated

Example:

map.xml:

<?xml version="1.0"?>

<Node Name="ParentNode">
    <Node Name="Child1" Src="Child1/"/>
    <Node Name="Child2" Src="Child2/"/>
    <Node Name="Child3" Src="Child3/"/>

    <Node Name="Child4">
        <Node Name="Child4_Sub1" />
        <Node Name="Child4_Sub2" Src="Child4_Sub2/"/>
    </Node>

    <Node Name="Child5" />
</Node>

A.xml:

<Node Name="ParentNode">
    <Node Name="Child4">
        <Node Name="Child4">
            <Node Name="Child4_Sub1">
                <!-- Here are many other elements -->
            </Node>
        </Node>
    </Node> 
    <!-- Here are many other elements -->
    <Node Name="Child1">
        <!-- Here are many other elements -->
    </Node>
    <!-- Here are many other elements -->

    <Node Name="ChildFoo">
        <!-- Here are many other elements -->
    </Node>
</Node>

The result should be:

<Node Name="ParentNode">
    <Node Name="Child4">
        <Node Name="Child4">
            <Node Name="Child4_Sub1">
                <!-- Here are many other elements -->
            </Node>
            <Node Name="Child4_Sub2" />
        </Node>
    </Node> 
    <!-- Here are many other elements -->
    <Node Name="Child1" Src="Child1" />
    <!-- Here are many other elements -->

    <Node Name="Child2" Src="Child2" />
    <Node Name="Child3" Src="Child3" />
</Node>

My XSLT script is:

<?xml version="1.0"?>
<xsl:stylesheet version="2.0">
    <xsl:param name="mapFile" required="yes"/>

    <xsl:variable name="MapDiagram" select="document($mapFile,/*)"/>
    <xsl:variable name="CurrentDocument" select="/" />

    <!-- handle Node elements in A.xml -->
    <xsl:template match="Node">
        <xsl:variable name="MyName" select="@Name"/>
        <xsl:choose>
            <xsl:when test="$MapDiagram//Node[@Name = $MyName]">
                <xsl:choose>
                    <xsl:when test="$MapDiagram//Node[@Name = $MyName]/@Src">
                        <xsl:copy-of select="$MapDiagram//Node[@Name = $MyName]"/>
                    </xsl:when>
                    <xsl:otherwise>
                        <Node Name="{@Name}" Type="{@Type}">
                            <xsl:apply-templates/>
                            <xsl:apply-templates select="$MapDiagram//Node[@Name = $MyName]" mode="MapDiagram" />
                        </Node>
                    </xsl:otherwise>
                </xsl:choose>
            </xsl:when>
            <xsl:otherwise>
                <xsl:message terminate="no">WARNING: Node "<xsl:value-of select="@Name"/>" not found in map file, ignoring</xsl:message>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

    <!-- handle Node elements from map file -->
    <xsl:template match="Node" mode="MapDiagram">
        <xsl:variable name="MyName" select="@Name"/>
        <xsl:choose>
            <xsl:when test="not($CurrentDocument//Node[@Name = $MyName])">
                <xsl:copy-of select="."/>
            </xsl:when>
            <xsl:otherwise>
                    <xsl:apply-templates mode="MapDiagram" />
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

    <!-- Copy all other elements in between -->
    <xsl:template match="*[name() != 'Node']">
        <xsl:copy-of select="."/>
    </xsl:template>
</xsl:stylesheet>

The script works fine. It processes A.xml and looks up each Node element in map.xml. Since @Src and non-@Src Nodes can be mixed, it is called recursively.

However, this script generates:

<Node Name="ParentNode">
    <Node Name="Child4">
        <Node Name="Child4">
            <Node Name="Child4_Sub1">
                <!-- Here are many other elements -->
            </Node>
            <Node Name="Child4_Sub2" />
        </Node>
    </Node> 
    <!-- Here are many other elements -->
    <Node Name="Child1" Src="Child1" />
    <!-- Here are many other elements -->

    <Node Name="Child2" Src="Child2" />
    <Node Name="Child3" Src="Child3" />
    <Node Name="Child4_Sub2" />
</Node>

So, the Child4_Sub2 is generated twice which is non-sense since Child4_Sub2 would need Child4 as parent anyway! But so far I found no way to prevent this element from being printed.

Do you have any hints?

Regards,
divB

Answer 1

Change:

      <xsl:apply-templates mode="MapDiagram" select=
        "$MapDiagram//Node[@Name = $MyName]"/>

to:

    <xsl:if test="not(@Name = ancestor::Node/@Name)">
      <xsl:apply-templates mode="MapDiagram" select=
        "$MapDiagram//Node[@Name = $MyName]"/>
    </xsl:if>

Here is a complete solution:

<xsl:stylesheet version="2.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output omit-xml-declaration="yes" indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:param name="mapFile"
        select="'file:///c:/temp/delete/map.xml'"/>

        <xsl:variable name="MapDiagram" select="document($mapFile,/*)"/>
        <xsl:variable name="CurrentDocument" select="/" />

        <!-- handle Node elements in A.xml -->
        <xsl:template match="Node">
            <xsl:variable name="MyName" select="@Name"/>
            <xsl:choose>
                <xsl:when test="$MapDiagram//Node[@Name = $MyName]">

                    <xsl:choose>
                        <xsl:when test="$MapDiagram//Node[@Name = $MyName]/@Src">
                            <xsl:copy-of select="$MapDiagram//Node[@Name = $MyName]"/>
                        </xsl:when>
                        <xsl:otherwise>
                            <Node Name="{@Name}" Type="{@Type}">
                                <xsl:apply-templates/>

                                <xsl:if test="not(@Name = ancestor::Node/@Name)">
                                  <xsl:apply-templates mode="MapDiagram" select=
                                     "$MapDiagram//Node[@Name = $MyName]"
                                  />
                                </xsl:if>
                            </Node>
                        </xsl:otherwise>
                    </xsl:choose>

                </xsl:when>
                <xsl:otherwise>
                    <xsl:message terminate="no">WARNING: Node "<xsl:value-of select="@Name"/>" not found in map file, ignoring</xsl:message>
                </xsl:otherwise>
            </xsl:choose>
        </xsl:template>

        <!-- handle Node elements from map file -->
        <xsl:template match="Node" mode="MapDiagram">
            <xsl:variable name="MyName" select="@Name"/>
            <xsl:choose>
                <xsl:when test="not($CurrentDocument//Node[@Name = $MyName])">
                    <xsl:copy-of select="."/>
                </xsl:when>
                <xsl:otherwise>
                        <xsl:apply-templates mode="MapDiagram" />
                </xsl:otherwise>
            </xsl:choose>
        </xsl:template>

        <!-- Copy all other elements in between -->
        <xsl:template match="*[name() != 'Node']">
            <xsl:copy-of select="."/>
        </xsl:template>
</xsl:stylesheet>

When this transformation is applied to the provided XML document:

<Node Name="ParentNode">
    <Node Name="Child4">
        <Node Name="Child4">
            <Node Name="Child4_Sub1"/>
        </Node>
    </Node>

    <Node Name="Child1"/>

    <Node Name="ChildFoo"/>
</Node>

and the provided “map.xml” is at C:\temp\delete\map.xml:

<Node Name="ParentNode">
    <Node Name="Child1" Src="Child1/"/>
    <Node Name="Child2" Src="Child2/"/>
    <Node Name="Child3" Src="Child3/"/>
    <Node Name="Child4">
        <Node Name="Child4_Sub1" />
        <Node Name="Child4_Sub2" Src="Child4_Sub2/"/>
    </Node>
    <Node Name="Child5" />
</Node>

The wanted result (not containing the unwanted repetition) is produced:

<Node Name="ParentNode" Type="">
   <Node Name="Child4" Type="">
      <Node Name="Child4" Type="">
         <Node Name="Child4_Sub1" Type=""/>
      </Node>
      <Node Name="Child4_Sub2" Src="Child4_Sub2/"/>
   </Node>
   <Node Name="Child1" Src="Child1/"/>
   <Node Name="Child2" Src="Child2/"/>
   <Node Name="Child3" Src="Child3/"/>
   <Node Name="Child4_Sub2" Src="Child4_Sub2/"/>
   <Node Name="Child5"/>
</Node>

General note: The code that is provided is quite complicated and messy — there might be other logical issues with it. No XSLT 2.0 language features are used — this is essentially an XSLT 1.0 solution. It would be a good idea to rewrite your code in a better form.