如何使用XSLT从具有编号出现次数的非结构化XML中选择值

Question

For a label printing function I'm trying to understand how I can use XSLT and value-of select to retrieve values from an unstructed xml-output.

See the example below where the tags I3 and I4 is related if the "occ" (occurence) number is equal between the two tags.

The I4 tag describes the type of value, and the I3 is the actual value. For instance: "I3" occ="1">123 is related to "I4" occ="1" other number.

example:

<field tag="I3" occ="1">123</field>
<field tag="I4" occ="1" lang="sv-SE" invariant="true">other number</field>
<field tag="I3" occ="2">324</field>
<field tag="I4" occ="2" lang="sv-SE" invariant="true">find number</field>
<field tag="I3" occ="3">1203</field>
<field tag="I4" occ="3" lang="sv-SE" invariant="true">FID</field>
<field tag="I3" occ="4">321-35-2000</field>
<field tag="I4" occ="4" lang="sv-SE" invariant="true">archive number</field>

Is there a way with XSLT 1.0 to do this kind of select operation? My knowledge is limited to how I could select for instance the tag I3 with occ=3, as such:

<xsl:value-of select="field[@tag='I3' and @occ='4']" /></xsl:text>

but the data I'm selecting values from will not be similiar each time (the occurance och the type-tag will not always have the same order, and sometimes on or several of the types will not exist).

Any suggestions? Thanks for any input!

The output I want is something like:

<data>other number: 123</data>
<data>find number: 324</data>
<data>FID: 1203</data>
<data>archive number: 321-35-2000</data> 

Updated output - I realised that I need each I4 tag as element name, otherwise the printer service cannot use the lines as source for printing output.

<?xml version="1.0" encoding="UTF-8"?>  
<output>  
  <variable name="other number">123</variable>  
  <variable name="find number">324</variable>  
  <variable name="FID">1203</variable>  
  <variable name="archive number">321-35-2000</variable>  
</output>

Answer 1

If you can be sure that one of the elements of the pair will always be there, you could use that element for your initial selection. Then use a key to retrieve the other member of the pair (which may or may not exist).

In this example we assume that <field tag="I3"> always exists:

XML

<fields>
    <field tag="I3" occ="1">123</field>
    <field tag="I4" occ="1" lang="sv-SE" invariant="true">other number</field>
    <field tag="I3" occ="2">324</field>
    <field tag="I4" occ="2" lang="sv-SE" invariant="true">find number</field>
    <field tag="I3" occ="3">1203</field>
    <field tag="I4" occ="3" lang="sv-SE" invariant="true">FID</field>
    <field tag="I3" occ="4">321-35-2000</field>
    <field tag="I4" occ="4" lang="sv-SE" invariant="true">archive number</field>
</fields>

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="*"/>

<xsl:key name="type" match="field[@tag='I4']" use="@occ" />

<xsl:template match="/fields">
    <output>
        <xsl:for-each select="field[@tag='I3']">
            <data>
                <xsl:value-of select="key('type', @occ)"/>
                <xsl:text>: </xsl:text>
                <xsl:value-of select="."/>
            </data>
        </xsl:for-each>
    </output>
</xsl:template>

</xsl:stylesheet>

Result

<?xml version="1.0" encoding="UTF-8"?>
<output>
  <data>other number: 123</data>
  <data>find number: 324</data>
  <data>FID: 1203</data>
  <data>archive number: 321-35-2000</data>
</output>

---

Added:

If you change:

            <data>
                <xsl:value-of select="key('type', @occ)"/>
                <xsl:text>: </xsl:text>
                <xsl:value-of select="."/>
            </data>

to:

            <variable name="{key('type', @occ)}">
                <xsl:value-of select="."/>
            </variable>

the result will be:

<?xml version="1.0" encoding="UTF-8"?>
<output>
  <variable name="other number">123</variable>
  <variable name="find number">324</variable>
  <variable name="FID">1203</variable>
  <variable name="archive number">321-35-2000</variable>
</output>

Read about attribute value templates .