Question

I need to remove some nodes in my xml file in which it contains certain method and by what order it appears for example here is the input:

<root> 
<node id="a">
    <section id="a_1">
        <item id="0">
            <attribute>
                <color>Red</color>
            </attribute>
        </item>
    </section>

    <section id="a_2">
        <item id="0">
            <attribute>
                <color>Red</color>
            </attribute>
        </item>
    </section>            
</node>

<node id="b">
    <section id="b_1">         
        <user id="b_1b" method="pause">
            <attribute>a</attribute>
        </user>      
        <user id="b_1b" method="run">
            <attribute>a</attribute>
        </user>             
        <user id="b_1a" method="run">
            <attribute>
                <name>John</name>
            </attribute>
        </user>

        <user id="b_1a" method="pause">
            <attribute>a</attribute>
        </user>
    </section>

    <section id="b_1" method="create">   

        <user id="b_1b" method="stop">
            <attribute>a</attribute>
        </user>            
        <user id="b_1a" method="stop">
            <attribute>a</attribute>
        </user>

        <user id="b_1b" method="run">
            <attribute>a</attribute>
        </user>
        <user id="b_1b" method="pause">
            <attribute>a</attribute>
        </user>
    </section>

    <section id="b_2">                
        <user id="b_1a" method="run">
            <attribute>
                <name>John</name>
            </attribute>
        </user>
    </section>
</node>

If I use this method:

<xsl:transform version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:my="http://localhost"
  exclude-result-prefixes="my">

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

  <xsl:template match=" user[not(@method eq 'stop' )][not(. is my:last(.))]
  | user[    @method eq 'stop' ][not(. is my:last(.))]
                     | user[not(@method eq 'stop')][my:last(.)/@method eq 'stop']"/>

          <!-- Get the last user for this section & user id -->
          <xsl:function name="my:last">
            <xsl:param name="user"/>
            <xsl:sequence select="($user/../../section[@id eq $user/../@id]
                                              /user   [@id eq $user/@id]
                                  )
                                  [last()]"/>
          </xsl:function>
</xsl:transform>

result will be:

<root>
    <node id="a">
        <section id="a_1">
            <item id="0">
                <attribute>
                    <color>
Red
                    </color>
                </attribute>
            </item>
        </section>
        <section id="a_2">
            <item id="0">
                <attribute>
                    <color>
Red
                    </color>
                </attribute>
            </item>
        </section>
    </node>
    <node id="b">
        <section id="b_1">
        </section>
        <section id="b_1" method="create">
            <user id="b_1a" method="stop">
                <attribute>
a
                </attribute>
            </user>
            <user id="b_1b" method="pause">
                <attribute>
a
                </attribute>
            </user>
        </section>
        <section id="b_2">
            <user id="b_1a" method="run">
                <attribute>
                    <name>
John
                    </name>
                </attribute>
            </user>
        </section>
    </node>
</root>

while the expected output is:

<root>
    <node id="a">
        <section id="a_1">
            <item id="0">
                <attribute>
                    <color>Red</color>
                </attribute>
            </item>
        </section>

        <section id="a_2">
            <item id="0">
                <attribute>
                    <color>Red</color>
                </attribute>
            </item>
        </section>            
    </node>

    <node id="b">
        <section id="b_1">                                           
        </section>

        <section id="b_1" method="create">               
            <user id="b_1a" method="stop">
                <attribute>a</attribute>
            </user>

            **<user id="b_1b" method="run">
                <attribute>a</attribute>
            </user>**
            <user id="b_1b" method="pause">
                <attribute>a</attribute>
            </user>
        </section>

        <section id="b_2">                
            <user id="b_1a" method="run">
                <attribute>
                    <name>John</name>
                </attribute>
            </user>
        </section>
    </node>
</root>

so this is how the order works. If ‘stop’ occurs last then any other node with other methods with the same user id (such as pause and run) will be removed.
But if it’s not then the node with ‘stop’ itself and All node before that ‘stop’ will be removed.

This has to be occurred in the same section id and it will delete only the user node (leave the section id even if it is empty after deletion of user node).
Hope the explanation it’s not confusing.

Thanks very much.

cheers,
John

Answer 1

Try this XSLT instead, which reduces the number of conditions, and will work in XSLT 1.0 too

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

   <!-- Ignore users with 'stop' method which are not the last such user -->
   <xsl:template match="user[@method='stop'][following::user[@method='stop']]"/>

   <!-- Match other users -->
   <xsl:template match="user">
      <!-- Copy the user if there isn't a following user with the same id and 'stop' method -->
      <xsl:if test="not(following::user[@id=current()/@id][@method='stop'])">
         <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
         </xsl:copy>
      </xsl:if>
   </xsl:template>

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

This should also generate the expected output