Keep XML fields and one child using XSLT

Question

I am trying to trim an XML document into a new XML document. I have the following XML:

<rpc-reply>
  <configuration changed-seconds="1450987515" changed-localtime="2015-12-24 20:05:15 UTC">
    <routing-instances>
      <instance>
        <name>SOMENAME</name>
        <instance-type>virtual-router</instance-type>
        <interface>
          <name>lo0.1</name>
        </interface>
        <protocols>
          <bgp>
            <group>
              <name>EBGP-TEST</name>
              <type>external</type>
              <neighbor>
                <name>1.1.1.1</name>
                <peer-as>7222</peer-as>
              </neighbor>
            </group>
          </bgp>
          <ospf>
            <area>
              <name>0.0.0.0</name>
              <comment>SOME COMMENT</comment>
              <interface>
                <name>all</name>
              </interface>
            </area>
          </ospf>
        </protocols>
      </instance>
    </routing-instances>
  </configuration>
  <cli>
    <banner>[edit]</banner>
  </cli>
</rpc-reply>

This is what I need:

<rpc-reply>
  <configuration changed-seconds="1450987515" changed-localtime="2015-12-24 20:05:15 UTC">
    <routing-instances>
      <instance>
        <name>SOMENAME</name>
        <protocols>
          <ospf>
            <area>
              <name>0.0.0.0</name>
              <comment>SOME COMMENT</comment>
              <interface>
                <name>all</name>
              </interface>
            </area>
          </ospf>
        </protocols>
      </instance>
    </routing-instances>
  </configuration>
</rpc-reply>

Here is the XSLT code I am using:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ns="match:ns" version="1.0">
  <xsl:output omit-xml-declaration="yes" indent="yes"/>
  <xsl:strip-space elements="*"/>

  <ns:WhiteList>
   <name>area</name>
   <name>interface</name>
   <name>instance</name>
   <name>metric</name>
  </ns:WhiteList>

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

 <xsl:template match="*[not(descendant-or-self::*[name()=document('')/*/ns:WhiteList/*])]"/>

 </xsl:stylesheet>

And it almost works:

<rpc-reply>
  <configuration changed-seconds="1450987515" changed-localtime="2015-12-24 20:05:15 UTC">
    <routing-instances>
      <instance>
        <interface/>
        <protocols>
          <ospf>
            <area>
              <interface/>
            </area>
          </ospf>
        </protocols>
      </instance>
    </routing-instances>
  </configuration>
</rpc-reply>

I just need the child "<name>" for the interesting elements (if there is one there) and bonus if I can somehow get the "<comment>" right above "<interface>" Tried different combinations but not sure how to do it.

@michael.hor257k The ones in the "whitelist" section, based my solution on this [answer](http://stackoverflow.com/a/5790798/62138) — salparadise, Dec 26 '15 at 09:22
Since `` is in the WhiteList, should `lo0.1` be in the desired output? — unutbu, Dec 26 '15 at 12:13
@unutbu ideally I like to skip that section of interface, but not a strong requirement — salparadise, Dec 26 '15 at 16:17
Should it be excluded because its XPath is `//instance/interface/name` or should it be excluded for some other reason? — unutbu, Dec 26 '15 at 20:29
Yep I think I will filter using xpath, already doing some of that before I transform the document. — salparadise, Dec 26 '15 at 20:52

score 3 · Accepted Answer · answered Dec 26 '15 at 09:30

I just need the child "<name>" for the interesting elements (if there is one there)

You could add a template to handle it specifically:

<xsl:template match="name[name(..)=document('')/*/ns:WhiteList/*]" priority="1">
    <xsl:copy>
        <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
</xsl:template>

and bonus if I can somehow get the "<comment>" right above "<interface>"

Similarly:

<xsl:template match="comment[following-sibling::*[1][self::interface]]" priority="1">
    <xsl:copy>
        <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
</xsl:template>

To avoid code repetition, try a more streamlined version:

<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
xmlns:ns="match:ns">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>

<ns:WhiteList>
    <name>area</name>
    <name>interface</name>
    <name>instance</name>
    <name>metric</name>
</ns:WhiteList>

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

<xsl:template match="*[not(descendant-or-self::*[name()=document('')/*/ns:WhiteList/*])]"/>

<xsl:template match="name[name(..)=document('')/*/ns:WhiteList/*]" priority="1">
    <xsl:call-template name="identity"/>
</xsl:template>

<xsl:template match="comment[following-sibling::*[1][self::interface]]" priority="1">
    <xsl:call-template name="identity"/>
</xsl:template>

</xsl:stylesheet>

Anyway to have a comment only if its not empty or matches "SOME TEXT" ? — salparadise, Dec 26 '15 at 09:42
"*What does "priority" do?*" It resolves conflicts when two or more templates match the same node. Without raising the priority explicitly, the added rules would have the same 0.5 priority as your last template. — michael.hor257k, Dec 26 '15 at 09:49
"*Anyway to have a comment only if its not empty or matches "SOME TEXT"*" Sure, just add another predicate. — michael.hor257k, Dec 26 '15 at 09:49

Keep XML fields and one child using XSLT

1 Answers1