CODEWITHSUNDEEP
xsltxpathgrouping
Peter
Peter

Reputation: 1796

XSLT: how to check numerous nodes for a certain value applied to all of them

I have the following simplified XML source:

<?xml version="1.0" encoding="UTF-8"?>
<MVKE>
<item>
    <MANDT>025</MANDT>
    <MATNR>000000000000000551</MATNR>
    <VMSTA>2</VMSTA>
</item>
<item>
    <MANDT>025</MANDT>
    <MATNR>000000000000000551</MATNR>
    <VMSTA>2</VMSTA>
</item>
<item>
    <MANDT>025</MANDT>
    <MATNR>000000000000000551</MATNR>   
    <VMSTA>2</VMSTA>
</item>
</MVKE>

and I need to compare the <VMSTA> values. If they are all "2" then my flag-value in the target XML should say "true" otherwise "false".

I have come up with this XSLT:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output indent="yes" method="xml" encoding="UTF-8"/>

<xsl:template match="/">
    <list>
        <xsl:apply-templates select="MVKE"/>
    </list>
</xsl:template>

<xsl:template match="MVKE">
    <flag>
        <xsl:for-each select="item">
            <xsl:choose>
                <xsl:when
                    test="(preceding-sibling::*[1]/VMSTA or self::*/VMSTA = current()/VMSTA) and (current()/VMSTA='2')">
                    <xsl:value-of select="'true'"/>
                </xsl:when>
                <xsl:otherwise>
                    <xsl:value-of select="'false'"/>
                </xsl:otherwise>
            </xsl:choose>
        </xsl:for-each>
    </flag>
</xsl:template>

</xsl:stylesheet>

but the output is always 

<?xml version="1.0" encoding="UTF-8"?>
<list>
<flag>truetruetrue</flag>
</list>

because of the <xsl:for-each>. I have also tried it with keys on <VMSTA> but that also gave me 3 values in <flag>. How can I compare the 3 properly and only get one value in <flag>? Am I just thinking to complicated?

Upvotes: 5

Views: 3953

Answers (3)

Zach Young
Zach Young

Reputation: 11223

I recommend using a key to get a group of nodes with different values for <VMSTA/>. If the group only has one node, then all the values are identical:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="xml" indent="yes"/>
  <xsl:strip-space elements="*" />
  <xsl:key name="dupes" match="VMSTA" use="."/>

  <xsl:template match="/">
      <xsl:variable name="vmsta-count"
                    select="count(//VMSTA[generate-id() =
                                   generate-id(key('dupes', .))])"/>
      <list>
        <flag>
          <xsl:choose>
            <xsl:when test="$vmsta-count = 1">
              <xsl:text>true</xsl:text>
            </xsl:when>
            <xsl:otherwise>
              <xsl:text>false</xsl:text>
            </xsl:otherwise>
          </xsl:choose>
        </flag>
      </list>
  </xsl:template>
</xsl:stylesheet>

When run against your provided source results in:

<?xml version="1.0"?>
<list>
  <flag>true</flag>
</list>

But, this is a general-case solution, and doesn't care about the actual value, just differences in value.

I hope this helps.

Upvotes: 1

Wayne
Wayne

Reputation: 60414

You don't need a for-each. Assuming the context node is an MVKE element (as in your example), the following expression returns true when all VMSTA elements have a string value equal to 2 (and false when any other value is present):

not(item/VMSTA[not(.='2')])

This works because of the implicit conversion of item/VMSTA[not(.='2')] into a boolean. A node-set's boolean value is true if and only if it is non-empty. Therefore, item/VMSTA[not(.='2')] is true whenever it selects at least one node, which is when there exists a VMSTA element whose string value is not 2. Wrapping the expression in not() produces its negation, which is the desired result.

Complete example:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:output indent="yes" method="xml" encoding="UTF-8"/>
    <xsl:template match="/">
        <list><xsl:apply-templates select="MVKE"/></list>
    </xsl:template>
    <xsl:template match="MVKE">
        <flag><xsl:value-of select="not(item/VMSTA[not(.='2')])"/></flag>
    </xsl:template>
</xsl:stylesheet>

Upvotes: 9

Dimitre Novatchev
Dimitre Novatchev

Reputation: 243529

Just use:

not(/*/*/VMSTA[not(. = '2')])

This XPath expression evaluates to false() if there exists an element /*/*/VMSTA, whose string value is different from the string "2".

Otherwise true().

This may be referred to as the "law of double negation`

Upvotes: 3

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