Add value to existing node in xml using XSLT

Question

in my xml i have node <action/> in different places through the document. Every action node should get the value "U".

I tried this but it did not work:

input xml :

<?xml version="1.0" encoding="UTF-8"?><operationsSchedule>
    <id>test</id>
    <operationsRequests>
        <operationsRequest>
            <id>20572152</id>
            <segmentRequirements>
                <segmentRequirement>
                    <id>W1</id>
                    <materialRequirements>
         <action/>

         <hierarchyScope>default</hierarchyScope>
         <materialDefinitionID>510000533</materialDefinitionID>
         <materialRequirementID>510000533_0004</materialRequirementID>
         <materialRequirementProperties>
            <materialRequirementProperty>
               <action/>
               <dataType>Text</dataType>
               <hierarchyScope>default</hierarchyScope>
               <materialDefinitionPropertyID>BAG_NR</materialDefinitionPropertyID>
               <materialRequirementPropertyID>BAG_NR</materialRequirementPropertyID>
               <materialRequirementPropertyValueTexts>
                  <materialRequirementPropertyValueText>
                     <languageID>EN</languageID>
                     <uiid>47275</uiid>
                     <value><![CDATA[1]]></value>
                  </materialRequirementPropertyValueText>
               </materialRequirementPropertyValueTexts>
               <materialUse>Other</materialUse>
               <requiredByRequestedSegmentResponse>Other</requiredByRequestedSegmentResponse>
            </materialRequirementProperty>
            <materialRequirementProperty>
               <action/>
               <dataType>Text</dataType>
               <hierarchyScope>default</hierarchyScope>
               <materialDefinitionPropertyID>SCENARIO</materialDefinitionPropertyID>
               <materialRequirementPropertyID>SCENARIO</materialRequirementPropertyID>
               <materialRequirementPropertyValueTexts>
                  <materialRequirementPropertyValueText>
                     <languageID>EN</languageID>
                     <uiid>47276</uiid>
                     <value><![CDATA[C]]></value>
                  </materialRequirementPropertyValueText>
               </materialRequirementPropertyValueTexts>
               <materialUse>Other</materialUse>
               <requiredByRequestedSegmentResponse>Other</requiredByRequestedSegmentResponse>
            </materialRequirementProperty>

                    </materialRequirements>
                </segmentRequirement>
            </segmentRequirements>
        </operationsRequest>
    </operationsRequests>
</operationsSchedule>

xsl:

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

 <xsl:template match="action">
  <xsl:copy>
      <xsl:apply-templates select="@*"/>
      <xsl:text>U</xsl:text>
    </xsl:copy>
 </xsl:template>

 <xsl:template match="materialRequirements"/>

</xsl:stylesheet>

Answer 1

You need to remove the <xsl:template match="materialRequirements"/> as that way the materialRequirements elements are not processed and obviously if the contain any action elements your template for them is never used.