XML Transform set attribute on specific child element

Question

I'm new to XML and so far I've managed to muddle along reading a few things and looking at answers to other peoples question but I'm stuck.

In the sample XML below and I need to transform <value>some interesting information</value> to be <value web_label="3" mobile_label="3">some interesting information</value>. Value is variable so the correct value element is the sibling of <name>Special Description</name> which is constant.

<job>
    <job_type>job</job_type>
    <third_party_id>AA123456-AA</third_party_id>
    <custom_fields>
        <custom_field>
            <name>Date Promised</name>
            <permission>read_only</permission>
            <value>2020-01-01T00:00:00Z</value>
        </custom_field>
            <custom_field>
            <name>Work Order</name>
            <permission>read_only</permission>
            <value>L1</value>
        </custom_field>
        <custom_field>
            <name>Special Description</name>
            <permission>read_only</permission>
            <value>some interesting information</value>
        </custom_field>
    </custom_fields>
</job>

In my trial and error I've managed to set the attributes on all the value elements using the below. I thought I could then replace match="/job/custom_fields/custom_field/value with match="/job/custom_fields/custom_field[name=Special Description]/value" to select the specific element but that errors.

Is there an xpath query I can use to achieve this/what is the best way to do this in my transform?

    <xsl:template match="/job/custom_fields/custom_field/value">
        <xsl:copy>
            <xsl:attribute name="web_label">3</xsl:attribute>
            <xsl:attribute name="mobile_label">3</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

The XSLT:

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

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

    <xsl:template match="/job/custom_fields/custom_field[name=Special Description]/value">
        <xsl:copy>
            <xsl:attribute name="web_label">3</xsl:attribute>
            <xsl:attribute name="mobile_label">3</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="custom_fields">
        <xsl:copy>
            <xsl:attribute name="type">array</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="third_party_id">
        <xsl:copy>
            <xsl:attribute name="web_label">2</xsl:attribute>
            <xsl:attribute name="mobile_label">2</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>

I appreciate the help.

Answer 1

Thanks to @michael.hor257 for suggesting

<xsl:template match="custom_field[name='Special Description']/value">
   <value web_label="3" mobile_label="3">
       <xsl:value-of select="."/>  
   </value>
</xsl:template>

For some reason when used in my existing XSLT I ended up with xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/ in the transformed XML.

<job>
    <job_type>job</job_type>
    <third_party_id web_label="2" mobile_label="2">AA123456-AA</third_party_id>
    <custom_fields type="array">
        <custom_field>
            <name>Date Promised</name>
            <permission>read_only</permission>
            <value>2020-01-01T00:00:00Z</value>
        </custom_field>
            <custom_field>
            <name>Work Order</name>
            <permission>read_only</permission>
            <value>L1</value>
        </custom_field>
        <custom_field>
            <name>Special Description</name>
            <permission>read_only</permission>
            <value xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
                web_label="3"
                mobile_label="3">some interesting information</value>
        </custom_field>
    </custom_fields>
</job>

Using @michael.hor257's xpath query with xsl:copy and xsl:attribute from my original XSLT however did the trick, so I ended up with:

    <xsl:template match="custom_field[name='Special Description']/value">
        <xsl:copy>
            <xsl:attribute name="web_label">3</xsl:attribute>
            <xsl:attribute name="mobile_label">3</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

Resulting complete XSLT:

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

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

    <xsl:template match="custom_field[name='Special Description']/value">
        <xsl:copy>
            <xsl:attribute name="web_label">3</xsl:attribute>
            <xsl:attribute name="mobile_label">3</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="custom_fields">
        <xsl:copy>
            <xsl:attribute name="type">array</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>

    <xsl:template match="third_party_id">
        <xsl:copy>
            <xsl:attribute name="web_label">2</xsl:attribute>
            <xsl:attribute name="mobile_label">2</xsl:attribute>
            <xsl:apply-templates select="node()" />
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>

And the transformed XML looks like this:

<job>
    <job_type>job</job_type>
    <third_party_id web_label="2" mobile_label="2">AA123456-AA</third_party_id>
    <custom_fields type="array">
        <custom_field>
            <name>Date Promised</name>
            <permission>read_only</permission>
            <value>2020-01-01T00:00:00Z</value>
        </custom_field>
            <custom_field>
            <name>Work Order</name>
            <permission>read_only</permission>
            <value>L1</value>
        </custom_field>
        <custom_field>
            <name>Special Description</name>
            <permission>read_only</permission>
            <value web_label="3" mobile_label="3">some interesting information</value>
        </custom_field>
    </custom_fields>
</job>

Answer 2

If you only want to modify a specific value element, match it using a predicate:

XSLT 1.0

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

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

<xsl:template match="custom_field[name='Special Description']/value">
    <value web_label="3" mobile_label="3">
        <xsl:value-of select="."/>  
    </value>
</xsl:template>

</xsl:stylesheet>